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A Publication of the Professional
Sections of the Canadian Diabetes Association
Une publication des sections professionnellesde l'Association canadienne du diabete
CONTENTS: April 2013 - Volume 37 - Supplement 1
S1 Introduction
S4 Methods
S8 De
nition, Classi
cation and Diagnosis of Diabetes, Prediabetes and Metabolic SyndromeS12 Screening for Type 1 and Type 2 Diabetes
S16 Reducing the Risk of Developing Diabetes
Management
S20 Organization of Diabetes Care
S26 Self-Management Education
S31 Targets for Glycemic Control
S35 Monitoring Glycemic Control
S40 Physical Activity and Diabetes
S45 Nutrition Therapy
S56 Pharmacotherapy in Type 1 Diabetes
S61 Pharmacologic Management of Type 2 Diabetes
S69 Hypoglycemia
S72 Hyperglycemic Emergencies in Adults
S77 In-hospital Management of Diabetes
S82 Weight Management in Diabetes
S87 Diabetes and Mental Health
S93 Inuenza and Pneumococcal Immunization
S94 Pancreas and Islet Transplantation
S97 Natural Health Products
Macrovascular and Microvascular Complications
S100 Vascular Protection in People with Diabetes
S105 Screening for the Presence of Coronary Artery Disease
(continued)Publication Mail Agreement 41536048 Return undeliverable Canadian addresses to:Transcontinental Printing, 737 Moray St, Winnipeg, MB R3J 3S9 Printed in Canada
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S110 Dyslipidemia
S117 Treatment of Hypertension
S119 Management of Acute Coronary Syndromes
S124 Management of Stroke in Diabetes
S126 Treatment of Diabetes in People with Heart Failure
S129 Chronic Kidney Disease in Diabetes
S137 Retinopathy
S142 Neuropathy
S145 Foot Care
S150 Erectile Dysfunction
Diabetes in Children
S153 Type 1 Diabetes in Children and Adolescents
S163 Type 2 Diabetes in Children and Adolescents
Diabetes in Special Populations
S168 Diabetes and Pregnancy
S184 Diabetes in the Elderly
S191 Type 2 Diabetes in Aboriginal Peoples
AppendicesS197 Appendix 1: Etiologic Classication of Diabetes Mellitus
S198 Appendix 2: Sample Diabetes Patient Care Flow Sheet for Adults
S200 Appendix 3: Examples of Insulin Initiation and Titration Regimens in People with Type 2Diabetes
S202 Appendix 4: Self-Monitoring of Blood Glucose (SMBG) Recommendation Tool forHealthcare Providers
S204 Appendix 5: Approximate Cost Reference List for Antihyperglycemic Agents
S207 Appendix 6: Therapeutic Considerations for Renal Impairment
S209 Appendix 7: Sick Day Medication List
S210 Appendix 8: Rapid Screening for Diabetic Neuropathy
S211 Appendix 9: Diabetes and Foot Care: A Patient’s Checklist
S212 Appendix 10: Diabetic Foot Ulcers: Essentials of Management
S212 Appendix 11: A1C Conversion Chart
CONTENTS (continued): April 2013 - Volume 37 - Supplement 1
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Can J Diabetes 37 (2013) A3–A13
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Acknowledgment / Can J Diabetes 37 (2013) A3–A13
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A Publication of the
Professional Sections of theCanadian Diabetes Association
Une publication des
sections professionnelles de
l'Association canadienne du diabete
Editor-in-Chief
David Lau MD PHD FRCPC
Editor Emeritus
Heather J. Dean MD FRCPC
Associate Editors
Lori Berard RN CDE
Sarah Capes MD MSC FRCPC
Alice Y.Y. Cheng MD FRCPC
J. Robin Conway MD
Carol Fawcett RD CDE
Rejeanne Gougeon PHD
Timothy J. Kieffer PHD
Sora Ludwig MD FRCPC
Gail MacNeill RN, MED CDE
Sara Meltzer MD FRCPC
Daniele Pacaud MD FRCPC
Rémi Rabasa-Lhoret MD PHD
Michael Riddell PHD
Elizabeth Sellers MD MSC FRCPC
Diana Sherifali RN PHD CDE
Scot H. Simpson BSP PHARMD MSC
T. Michael Vallis PHD R.PSYCH
National Editorial Board
Gillian Booth MD MSC FRCPC
Peter E. Light PHD
Peter A. Senior MBBS PHD
Arya M. Sharma MD PHD FRCPC
Garry X. Shen MD PHD
International Editorial Board
Stephanie Amiel MD FRCP
Barbara J. Anderson PHD
Alan Baron MD
Stuart J. Brink MD
Suad Efendic MD PHD
George Eisenbarth MD PHDMartha Funnell RN MS CDE
Diana Guthrie PHD RN CDE
Phillipe Halban PHD
Len Harrison MD DSC FRACP
FRCPA
Robert Henry MD
Cheri Ann Hernandez RN PHD CDE
Ryuzo Kawamori MD PHDKarmeen Kulkarni RD MS CDE
Willy Malaisse MD PHD
Kathy Mulcahy RN MSN CDE
Stephen O'Rahilly MD FRCOI FRCF
Daniel Porte, Jr. MD
Paul Robertson MD
Alicia Schiffrin MD
Meng Tan MD FACP FRCPCVirginia Valentine RN MS CDE
Paul Zimmett AM
Managing Editor
Ryan Moffat
Publications Coordinator
Alarica Fernandes
mailto:[email protected]:[email protected]:[email protected]:[email protected]
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Notes to Readers
Overview
The Canadian Diabetes Association 2013 Clinical Practice Guide-
lines for the Prevention and Management of Diabetes in Canada are
intendedto guidepractice and are not intended to serve as a compre-
hensive text of diabetes management, nor are they intended to set
criteria for research protocols. These guidelines are intended to
inform general patterns of care. These guidelines are also intended
to enhance diabetes prevention efforts in Canada and to reduce the
burden of diabetes complications in people living with this disease.
As per the Canadian Medical Association Handbook on Clinical
Practice Guidelines (Davis D, et al. Ottawa, ON: Canadian Medical
Association; 2007), guidelines should not be used as a legal
resource in malpractice cases as “their more general nature renders
them insensitive to the particular circumstances of the individual
cases.” Healthcare professionals must consider the needs, values
and preferences of individual patients, use clinical judgement andwork with available human and healthcare service resources in
their settings. These guidelines were developed using the best
available evidence. It is incumbent upon healthcare professionals
to stay current in this rapidly changing eld.
Unless otherwise specied, these guidelines pertain to the care
of adults with diabetes. Two chaptersdType 1 Diabetes in Children
and Adolescents and Type 2 Diabetes in Children and Adoles-
centsdare included to highlight aspects of care that must be
tailored to the pediatric population.
Suggested Citation
To cite as a whole:Canadian Diabetes Association Clinical Practice Guidelines
Expert Committee. Canadian Diabetes Association 2013 Clinical
Practice Guidelines for the Prevention and Management of Diabetes
in Canada. Can J Diabetes 2013;37(suppl 1):S1-S212.
To cite a specic chapter:
Last, First M. "Chapter Title." Journal Year;Vol(Number):XX-XX.
Example:
Harper W, Clement M, Goldenberg R, et al. Canadian Diabetes
Association 2013 Clinical Practice Guidelines for the Prevention
and Management of Diabetes in Canada: pharmacologic
management of type 2 diabetes. Can J Diabetes 2013;37(suppl 1):
S61-S68.
Reproduction of the Guidelines
Reproduction of the Canadian Diabetes Association 2013 Clinical
Practice Guidelines for the Prevention and Management of Diabetes
in Canada, in whole or in part, is prohibited without written
consent of the publisher.
Extra Copies
Copies of this document may be ordered, for a nominal fee, at
orders.diabetes.ca.
To order 50 or more copies for educational, commercial or
promotional use, contact Zoe Aarden, Elsevier Canada, 905 King
St. W, Toronto, ON M6K 3G9; E-mail: [email protected].
Website
These guidelines are available at guidelines.diabetes.ca.
mailto:[email protected]:guidelines.diabetes.camailto:guidelines.diabetes.camailto:[email protected]
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Clinical Practice Guidelines
Introduction
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee
The initial draft of this chapter was prepared by Alice Y.Y. Cheng MD, FRCPC
Every 5 years,since 1992,the Clinical & Scientic Section (C&SS) of
the Canadian Diabetes Association has published comprehensive,
evidence-based recommendations for healthcare professionals to
consider in the prevention and management of diabetes in Canada.They have served as a helpful resource and aid for anyone caring for
people with diabetes and are recognized, not only in Canada but also
internationally, as high-quality, evidence-based clinical practice
guidelines (1). In fact, an analysis by Bennett et al (1) demonstrated
that the Canadian Diabetes Association clinical practice guidelines
are among the best in the world with respect to quality, rigour and
process (1). For these 2013 Clinical Practice Guidelines for the
Prevention and Management of Diabetes in Canada, volunteer
members of the Clinical Practice Guidelines Expert Committee
assessed the peer reviewed evidence published since 2008 relevant
to the prevention and management of diabetes. They then incorpo-
rated the evidence into revised diagnostic, prognostic and thera-
peutic recommendations for the care of Canadians living with
diabetes, as well as recommendations for measures to delay theonsetof diabetes for populations at high risk of developing type 2 diabetes.
A number of important changes have occurred in the develop-
ment of the 2013 clinical practice guidelines:
Expansion of the Expert Committee to include 120 healthcare
professional volunteers from across Canada; Expert Committee
members bring expertise from diverse practice settings and
include professionals from family medicine, endocrinology,
internal medicine, infectious disease, neurology, nephrology,
cardiology, urology, psychology, obstetrics, ophthalmology, pedi-
atrics,nursing,dietetics, pharmacy, exercisephysiologyand others.
Inclusion and active participation of people with diabetes on
the Expert Committee to ensure that their views and prefer-
ences informed the guideline development process and therecommendations.
Update and expansion of previous chapters and, in some cases,
amalgamation of previous chapters into others to increase
utility and relevance.
Inclusion of a drug cost appendix for pharmacological thera-
pies as a reference for clinicians.
Update and expansion of our Methodology process (e.g.
updated literature searches throughout the guideline devel-
opment process, expansion of the Duality of Interest policy)
(see Methods chapter, p. S4).
Inclusion of a “Practical Tips” box, where appropriate, to facil-
itate implementation of the recommendations.
Expanded harmonization of recommendations through
collaboration with other organizations, including the Canadian
Hypertension Education Program (CHEP), the Society of Obste-
tricians and Gynecologists of Canada (SOGC), the CanadianCardiovascular Society (CCS) and the Canadian Cardiovascular
Harmonization of National Guidelines Endeavour (C-CHANGE).
Expanded dissemination and implementation strategy with
increased use of technology.
It is hoped that primary care physicians and other healthcare
professionals who care for people with diabetes or those at risk of
diabetes will continue to nd the evidence compiled in these
guidelines a vital aid and resource in their efforts. We are condent
that, ultimately, if applied properly, these guidelines will lead to
improved quality of care, reduced morbidity and mortality from
diabetes and its complications, and a better quality of life for people
living with this chronic disease.
The Challenge of Diabetes
Diabetes mellitus is a serious condition with potentially devas-
tating complications that affects all age groups worldwide. In 1985,
an estimated 30 million people around the world were diagnosed
with diabetes; in 2000, that gure rose to over 150 million; and, in
2012, the International Diabetes Federation (IDF) estimated that
371 million people had diabetes (2). That number is projected to
rise to 552 million (or 1 in 10 adults) by 2030, which equates to 3
new cases per second (2). Although the largest increase is expected
to be in countries with developing economies, Canada also will be
impacted signicantly. As of 2009, the estimated prevalence of
diabetes in Canada was 6.8% of the populationd2.4 million Cana-
dians (3)d
a 230% increase compared to prevalence estimates in1998. By 2019, that number is expected to grow to 3.7 million (3).
Diabetes is the leading cause of blindness, end stage renal disease
(ESRD) and nontraumatic amputation in Canadian adults. Cardio-
vascular disease is the leading cause of death in individuals with
diabetes and occurs 2- to 4-fold more often than in people without
diabetes. People with diabetes are over 3 times more likely to be
hospitalized with cardiovascular disease, 12 times more likely to be
hospitalized with ESRD and over 20 times more likely to be
hospitalized for a nontraumatic lower limb amputation compared
to the general population (3). Diabetes and its complications
increase costs and service pressures on Canada’s publicly funded
healthcare system. Among adults aged 20 to 49 years, those with
Contents lists available at SciVerse ScienceDirect
Canadian Journal of Diabetesj o u r n a l h o m e p a g e :
w w w . c a n a d i a n j o u r n a l o f d i a b e t e s . c o m
1499-2671/$ e see front matter 2013 Canadian Diabetes Association
http://dx.doi.org/10.1016/j.jcjd.2013.01.009
Can J Diabetes 37 (2013) S1eS3
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diabetes were 2 times more likely to see a family physician and 2 to
3 times more likely to see a specialist (3). Also, peoplewith diabetes
were 3 times more likely to require hospital admission in the
preceding year with longer lengths of stay (3). Therefore, the
impact of diabetes is signicant not only for individuals but also for
their families and for society as a whole.
Delaying the Onset of Type 2 Diabetes
Prevention of type 1 diabetes has not yet been successful, butremains an active area of research. However, there is good evidence
that delayingthe onsetof type 2 diabetesresultsin signicant health
benets, including lower rates of cardiovascular disease and renal
failure (4). In 2007, the IDF releaseda “Consensuson Type 2 Diabetes
Prevention” and called upon the governments of all countries to
develop and implementa National Diabetes Prevention Plan (4). The
IDF proposed that strategies be implemented for 2 separate groups:
those at high risk of developing type 2 diabetes, and the entire
population at large. Among those at high risk, the proposed 3-step
approach was to A) identify those who may be at higher risk, B)
measure therisk,and C) intervene to delay/preventthe onsetof type
2 diabetes usingpredominantly health behaviourstrategies to affect
the modiable risk factors for type 2 diabetes. As of 2013, Canada
does not have such a strategy in place. There remains an urgent andincreasing need for governments to invest in research to dene
effective strategies andprogramsto prevent andtreatobesityand to
encourage physical activity. In addition, Canada’s diverse pop-
ulation, with some ethnic groups disproportionally affected by
diabetes, requires that health promotion, and disease prevention
and management strategies be culturallyappropriateand tailored to
specic populations. They also should include policies aimed at
addressing poverty and other systemic barriers to healthcare (5).
Optimal Care of Diabetes
Effectivediabetes careshould be delivered within the framework
of the Chronic Care Model and centred around the individual who is
practicing, and supported in, self-management (see Organization of Care chapter, p. S20). To achieve this, an interprofessional team with
the appropriate expertise is required, and the system needs to
support and allow for sharing and collaboration between primary
care and specialist care as needed. A multifactorial approach
utilizing an interprofessional team addressing healthy behaviours,
glycemic control, blood pressure control, lipid management and
vascular protection measures has been shown to effectively and
dramatically lower the risk of development and progression of
serious complications for individuals with diabetes (6e9). In addi-
tion, individuals with diabetes must be supported in the skills of
self-management sincetheir involvementin disease management is
absolutely necessary for success. People with diabetes require
training in goal setting, problem solving and health monitoring, all
of which are critical components of self-management. They alsoneed accessto a broad rangeof tools,including medications,devices
andsupplies to help them achieve therecommended blood glucose,
cholesterol and blood pressure targets. Health outcomes depend on
managing the disease effectively, and, without access to the neces-
sary tools and strategies, Canadians living with diabetes will not be
able to achieve optimal results. All levels of government should
commit to investingin chronic care management andsupport of the
tools needed for successful self-management to ensure that optimal
care can be delivered.
Research
Canada continues to be a world leader in diabetes research. This
researchis essential forcontinued improvement in thelivesof people
withdiabetes. Regulatory agencies should not apply these guidelines
in a rigid way with regard to clinical research in diabetes. It is sug-
gested that study protocols may include guideline recommenda-
tions, but individual decisions belong in the domain of the patient-
physician relationship. The merits of each research study must be
assessed individually so as to not block or restrict the pursuit of new
information. The Canadian Diabetes Association welcomes the
opportunity to work withregulatory agencies to enhance researchin
Canada and, ultimately, to improve the care of people with diabetes.
Cost Considerations
When it comes to the issue of cost, caution is required when
identifying direct, indirect and induced costs for treating diabetes
(10). In fact, the 2011 Diabetes in Canada report from the Public
Health Agency of Canadacouldnot reportthe total economic burden
of diabetes, but concluded that the costs will only increase
substantiallyas the prevalence of the disease increases overtime (3).
Nonetheless, in 2009, the Canadian Diabetes Association commis-
sioned a report to evaluate the economic burden of diabetes using
a Canadian Diabetes Cost Model, which utilizes the data from the
Canadian National Diabetes Surveillance System (NDSS) and the
Economic Burden of Illness in Canada (EBIC) (11). In this report, the
estimatedeconomicburdenof diabetes was$12.2billionin 2010 andprojected to increase by another $4.7 billion by 2020. It is certainly
the hope and expectation of all stakeholders that the evidence-
based prevention and management of diabetes in a multifactorial
fashion will reduce the economic burden of the disease (3,6,12).
These clinical practice guidelines, like those published before,
have purposefully not taken into account cost effectiveness in the
evaluation of the evidencesurrounding best practice. The numerous
reasons forthis have been outlined in detailpreviously (13). Someof
these reasons include the paucity of cost-effectiveness analyses
using Canadian data, the dif culty in truly accounting for all the
important costs (e.g. hypoglycemia) in any cost-effectiveness
analysis, the lack of expertise and resources to properly address
the cost-effectiveness analyses needed for all the clinical questions
within these clinical practice guidelines and, perhaps more impor-tantly, the philosophical question of which is more important:
clinical benet to the patient or cost to the system? At what level of
cost effectiveness should one consider a therapy worth recom-
mending?For these2013 clinical practice guidelines, the questionof
whether the committee should incorporate cost considerations was
discussed again, and a Cost Consideration Working Group, consist-
ing of health economists and health outcomes researchers, was
convened. Themandateof thegroup was todevelopa proposalto the
Clinical Practice Guidelines SteeringCommitteedescribing how cost
issues might be incorporated into the guidelines, considering
feasibility and impact. Based on issues of feasibility and philosoph-
icalconsiderations of our roleas recommendation developers, it was
decided that cost would not be included in the recommendations to
ensure that they reect the best available clinical evidence for thepatient. The issue of evidence-based vs. cost-effective healthcare is
an ethical debate that should involve all citizens because the
outcome of thisdebateultimately impacts every Canadian.However,
it is recognized and acknowledged that both the healthcare profes-
sional and the patient should consider cost when deciding on ther-
apies.Therefore, drug costs areincluded in Appendix 5, allowing for
easy reference for both clinicians and patients alike.
Other Considerations
In Canada, the glycated hemoglobin (A1C) continues to be re-
ported using National Glycohemoglobin Standardization Program
(NGSP) units (%). In 2007, a consensus statement from the American
Diabetes Association, the European Association for the Study of
A.Y.Y. Cheng / Can J Diabetes 37 (2013) S1eS3S2
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Diabetes and the IDF called for A1C reporting worldwide to change
to dual reportingof A1Cwith the International Federation of Clinical
Chemistry and Laboratory Medicine (IFCC) SI units (mmol/mol) and
derived NGSP units (%)with the hope of fullyconverting to exclusive
reporting in SI units (14). However, this has not been adopted
worldwide, with both Canada and the United States still using the
NGSP units (%) (15). Although there are some advantages to
reporting in SI units, the most notable disadvantage is the massive
education effort that would be required to ensure recognition and
adoption of the new units. At this time, Canada is not performingdual reporting. Therefore, throughout this document, the A1C will
still be written in NGSP units (%). For those who wish to convert
NGSP units to SI units, the following equation can be used: (16)
IFCC ¼ 10.93(NGSP) e 23.50.
Dissemination and Implementation
Despite the strength of the evidence supporting the multifacto-
rial treatment of people with diabetes to reduce complications,
a recent national cross-sectional survey conducted around World
Diabetes Day (November 14, 2012) demonstrated that only 13% of
5123 patients with type 2 diabetes had achieved all 3 metabolic
targets (glycemia, lipids and blood pressure) (17). Therefore, a care
gap remains and the effectivedissemination andimplementationof these 2013 clinical practice guidelines is critical. A Dissemination &
Implementation Chair was appointed at the beginning of the
guidelines process. Strategies were developed to increase practi-
tioner implementation and to improve patient care and health
outcomes. A Dissemination & Implementation Committee was
created to develop a strategic plan to be implemented at the launch
of the guidelines and to continue for years thereafter. These volun-
teers from across Canada are involved in creating a 3-year plan to
translate the evidence compiled in the guidelines into community
practice. An Executive Summary will be distributed to healthcare
professionals in Canada. The full guidelines will continue to be
available online, and summary articles will be strategically placed in
journals and newsletters. In addition, key messages and tools sup-
porting specic themes from the guidelines will be highlighted intechnology-based and paper-based awareness campaigns over the
next few years. Primary care physicians, healthcare providers,
government of cials, Canadiansliving with diabetes and the general
public continue to be the audiences for these campaigns.
Clinical Practice Guidelines and Clinical Judgement
“ Neither evidence nor clinical judgment alone is suf cient.
Evidence without judgment can be applied by a technician. Judgment
without evidence can be applied by a friend. But the integration of
evidence and judgment is what the healthcare provider does in order
to dispense the best clinical care.” (Hertzel Gerstein, 2012)
People with diabetes are a diverse and heterogeneous group;
therefore, it must be emphasized that treatment decisions need to
be individualized. Guidelines are meant to aid in decision making
by providing recommendations that are informed by the best
available evidence. However, therapeutic decisions are made at the
level of the relationship between the healthcare professional and
the patient. That relationship, along with the importance of clinical
judgement, can never be replaced by guideline recommendations.
Evidence-based guidelines try to weigh the benet and harm of
various treatments; however, patient preferences are not always
included in clinical research, and, therefore, patient values and
preferences must be incorporated into clinical decision making
(18). For some of the clinical decisions that we need to make with
our patients, strong evidence is available to inform those decisions,
and these are reected in the recommendations within these
guidelines. However, there are many other clinical situations where
strong evidence may not be available, or may never become
available, for reasons of feasibility. In those situations, the
consensus of expert opinions, informed by whatever evidence is
available, is provided to help guide and aid the clinical decisions
that need to be made at the level of the patient. It is also important
to note that clinical practice guidelines are not intended to be
a legal resource in malpractice cases as outlined in the Canadian
Medical Association Handbook on Clinical Practice Guidelines (19).
Conclusions
Diabetes is a complex and complicated disease. The burgeoning
evidence on new technologies and therapeutic treatments is
rapidly expanding our knowledge and ability to manage diabetes
and its complications; at the same time, however, it is challenging
for physicians and other healthcare professionals who care for
people with diabetes. These 2013 clinical practice guidelines
contain evidence-based recommendations that provide a useful
reference tool to help healthcare professionals translate the best
available evidence into practice. The hope is that these guidelines
will provide government of cials with the evidence they need
when rationalizing access to healthcare so that the potentially
benecial health outcomes are maximized for people living with
diabetes. Healthcare professionals are encouraged to judge inde-pendently the value of the diagnostic, prognostic and therapeutic
recommendations published in the 2013 Clinical Practice Guide-
lines for the Prevention and Management of Diabetes in Canada.
References
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2. International Diabetes Federation. IDF Diabetes Atlas. 5th ed. Brussels: Inter-national Diabetes Federation, www.idf.org/diabetesatlas; 2012. AccessedFebruary 21, 2013.
3. Public Health Agency of Canada. Diabetes in Canada: Facts and Figures froma Public Health Perspective. Ottawa; 2011.
4. Alberti KGMM, Zimmet P, Shaw J. International Diabetes Federation:a consensus on type 2 diabetes prevention. Diabet Med 2007;24:451e63.
5. McManus R. Time for action: a Canadian proposal for primary prevention of type 2 diabetes. Can J Diabetes 2012;36:44e9.
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Clinical Practice Guidelines
Methods
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee
The initial draft of this chapter was prepared by Gillian Booth MD, MSc, FRCPC,Alice Y.Y. Cheng MD, FRCPC
Process
Following the process used to develop previous Canadian Dia-
betes Association clinical practice guidelines (1,2), an ExecutiveCommittee, Steering Committee and Expert Committee with broad
expertise and geographic representation were assembled. In total,
120 volunteers,including health professionals fromfamilymedicine,
endocrinology, internal medicine, infectious disease, neurology,
nephrology, cardiology, urology, psychology, obstetrics, ophthal-
mology, pediatrics, nursing, dietetics, pharmacy, exercise physiology
and others, as well as people with diabetes, participated in the
guideline development process.
The following basic principles were adopted to ensure that the
values and empirical basis underlying each recommendation were
explicitly identied andto facilitate thecriticalscrutiny and analysis
of each recommendation by other organizations and individuals.
Elements covered by the Appraisal of Guidelines for Research
and Evaluation (AGREE) II instrument were incorporated into theguideline development process.
Each recommendation had to address a clinically important
question related to 1 or more of the following: detection,
prognosis, prevention or management of diabetes and its
sequelae. Health benets, risks and side effects of interventions
were considered in formulating the recommendations. Patient
preferences and values were sought from expert panel
members with diabetes and the literature (where available).
Whenever possible, each recommendation had to be justied
by the strongest clinically relevant, empirical evidence that
could be identied; the citation(s) reporting this evidence had
to be noted adjacent to the relevant guideline.
The strength of this evidence, based on prespecied criteriafrom the epidemiological literature and other guidelines
processes, had to be noted (3e8).
Each recommendation had to be assigned a grade based on the
available evidence, its methodological strength and its appli-
cability to the Canadian population.
Each recommendation had to be approved by the Steering
Committee and Executive Committee, with 100% consensus.
Guidelines based on biological or mechanistic reasoning,
expert opinion or consensus had to be explicitly identied and
graded as such; harmonization was sought with other Cana-
dian guideline bodies, including the Canadian Cardiovascular
Society (CCS), the Canadian Hypertension Education Program
(CHEP), the Canadian Cardiovascular Harmonization of
National Guidelines Endeavour (C-CHANGE) and the Society of
Obstetricians and Gynecologists of Canada (SOGC).
Identifying and Appraising the Evidence
Authors for each chapter were assembled based on their relevant
elds of expertise. Each chapter had 1 lead author, 1 or 2 “evidence
resource” persons trained or experienced in clinical epidemiology or
clinical research methodology, and additional authors, as needed. At
the outset of the process, committee members from each section of
the guidelines attended a workshop on evidence-based method-
ology,in order to ensure a consistent approachto the development of
recommendations. Committee members identied clinically impor-
tant questions related to diagnosis, prognosis, prevention and treat-
ment of diabetes andits complications,which were used as a basis for
our literature search strategy (outlined below).
Authors were to explicitly dene A) the population to whicha guidelinewould apply; B) thetest,risk factoror interventionbeing
addressed; C) the “gold standard” test or relevant intervention to
which thetest or interventionin questionwascompared; andD) the
clinically relevant outcomes being targeted. This information was
used to develop specic, clinically relevant questions that were the
focus of literature searches. For each question, individual strategies
were developed combining diabetes terms with methodological
terms. A librarian with expertise in literature reviews performed
a comprehensive search of the relevant English-language, pub-
lished, peer-reviewed literature using validated search strategies
(http://hiru.mcmaster.ca/hiru/) of electronic databases (MEDLINE,
EMBASE, CINAHL, the Cochrane Central Register of Trials, and
PsycINFO [where appropriate]). This was complemented by the
authors’ own manual and electronic searches.
Fortopics that werecovered in the2008 guidelines, theliterature
searches focused on new evidence published since those guidelines,
including literature published in September 2007 or later. For new
topics, the search time frame included the literature published since
1990 or earlier, where relevant. Updated literature searches were
performed at regular intervals throughout the development process.
Key citations retrieved from the literature searches were then
reviewed. Each citation that was used to formulate or revise
a recommendationwas assigned a levelof evidence accordingto the
prespecied criteria in Table 1, reecting the methodological quality
of the paper. When evaluating papers, authors were required to use
standardized checklists that highlighted the most important
Contents lists available at SciVerse ScienceDirect
Canadian Journal of Diabetesj o u r n a l h o m e p a g e :
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1499-2671/$ e see front matter 2013 Canadian Diabetes Association
http://dx.doi.org/10.1016/j.jcjd.2013.01.010
Can J Diabetes 37 (2013) S4eS7
http://hiru.mcmaster.ca/hiru/http://www.sciencedirect.com/science/journal/14992671http://www.canadianjournalofdiabetes.com/http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://dx.doi.org/10.1016/j.jcjd.2013.01.010http://www.canadianjournalofdiabetes.com/http://www.sciencedirect.com/science/journal/14992671http://hiru.mcmaster.ca/hiru/
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elements of a well-conducted study. The level of evidence was then
determined by the cited paper’s objectives, methodological rigour,
susceptibility to bias and generalizability (Table 1). Becausethey could not be critically appraised, meeting abstracts, narrative
review articles, news reports and other sources could not be used
to support recommendations. Papers evaluating the cost effective-
ness of therapies or diagnostic tests also were not included.
A number of considerations were made when evaluating the
evidencewithina given area. Forexample, peoplewith diabetes areat
high risk for several sequelae that are not exclusive to diabetes (e.g.
cardiovasculardisease, renalfailure and erectile dysfunction).As such,
some evidence relating to these problems was identied that either
excluded, did not report on or did not focus on people with diabetes.
Whenever such evidence was identied, a level was assigned
using the approach described above. Higher levels were assigned if
A) people with diabetes comprised a predened subgroup; B) the
results in the diabetes subgroup were unlikely to have occurred by
chance; andC) the evidence was generated in responseto questions
that were formulated prior to the analysis of the results. Lower
levels (than those indicated in Table 1) were assigned to evidence
that did not meet these criteria.
Guideline Development
Expert Committee members evaluated the relevant literature,
and guidelines were developed and initially reviewed by the Expert
Committee. In the absence of new evidence since the publication of the 2008 clinical practice guidelines, recommendations from the
2008 document were not changed.
The studies used to develop and support each recommendation
are cited beside the level of evidence. In some cases, key citations
that inuenced the nal recommendation were not assigned the
same level of evidence but ratherwere of varying levelsof evidence.
In those circumstances, all relevant studies were cited, regardless of
the grading assigned to the recommendation. The nal grading
depended on the overall evidence available, including the relative
strengths of the studies from a methodological perspective and the
studies’ ndings. Studies with conicting outcomes were also
considered and cited in the nal recommendation where relevant.
Further details on the grading process are described below.
Finally, several treatment recommendations were based onevidence generated from the use of one therapeutic agent from
a given class (e.g. one of the statins). Whenever evidence relating to
1 or more agents from a recognized class of agents was available,
the recommendation was written so as to be relevant to the class,
but specically studied therapeutic agents were identied within
the recommendation and/or cited reference(s). Only medications
with Health Canada Notice of Compliance granted by February 15,
2013 were included in the recommendations.
Grading the Recommendations
After formulating new recommendations or modifying existing
ones based on new evidence, each recommendation was assigned
a grade from A through D (Table 2). The highest possible grade that
a recommendation could have wasbased on thestrengthof evidence
that supported the recommendation (i.e. the highest level of
evidence assigned to studies on which the recommendation was
based). However, the assigned grading was lowered in some cases,
for example, if the evidence was found not to be applicable to the
Canadianpopulation or, if based on the consensusof the Steering and
Executive Committees, there wereadditional concerns regarding the
recommendation. In some situations, the grading also was lowered
for subgroups that were not well represented in the study or in
whom the benecial effectof an interventionwas less clear. Grading
also was lowered if thendings fromrelevant (and equally rigorous)
studies on thetopicwereconicting. Thus,a recommendationbased
on Level 1 evidence, deemed to be very applicable to Canadians
and supported by strong consensus, was assigned a grade of A.
A recommendation not deemed to be applicable to Canadians, or
judged to require further supporting evidence,was assigned a lower
grade. Where available,the number of patients that would needto be
treated in order to prevent 1 clinical event (number needed to treat
[NNT])or to causean adverse event(number needed toharm[NNH])
was considered in assessing the impact of a particular intervention.
Table 1
Criteria for assigning levels of evidence to the published studies
Level Criteria
Studies of diagnosis
Level 1 a) Independent interpretation of test results (without
knowledge of the result of the diagnostic or gold standard)
b) Independent interpretation of the diagnostic standard
(without knowledge of the test result)
c) Selection of people suspected (but not known) to have
the disorder
d) Reproducible description of both the test and diagnosticstandard
e) At least 50 patients with and 50 patients without the
disorder
Level 2 Meets 4 of the Level 1 criteria
Level 3 Meets 3 of the Level 1 criteria
Level 4 Meets 1 or 2 of the Level 1 criteria
Studies of treatment and prevention
Level 1A Systematic overview or meta-analysis of high quality RCTs
a) Comprehensive search for evidence
b) Authors avoided bias in selecting articles for inclusion
c) Authors assessed each article for validity
d) Reports clear conclusions that are supported by the data
and appropriate analyses
OR
Appropriately designed RCT with adequate power to answer
the question posed by the investigators
a) Patients were randomly allocated to treatment groups
b) Follow-up at least 80% complete
c) Patients and investigators were blinded to the treatment*
d) Patients were analyzed in the treatment groups to which
they were assigned
e) The sample size was large enough to detect the outcome
of interest
Level 1B Nonrandomized clinical trial or cohort study with indisputable
results
Level 2 RCT or systematic overview that does not meet Level 1 criteria
Level 3 Nonrandomized clinical trial or cohort study; systematic
overview or meta-analysis of level 3 studies
Level 4 Other
Studies of prognosis
Level 1 a) Inception cohort of patients with the condition of interest
but free of the outcome of interestb) Reproducible inclusion/exclusion criteria
c) Follow-up of at least 80% of subjects
d) Statistical adjustment for extraneous prognostic factors
(confounders)
e) Reproducible description of outcome measures
Level 2 Meets criterion a) above, plus 3 of the other 4 criteria
Level 3 Meets criterion a) above, plus 2 of the other criteria
Level 4 Meets criterion a) above, plus 1 of the other criteria
RCT , randomized, controlled trial.
* In cases where such blinding was not possible or was impractical (e.g. intensive
vs. conventional insulin therapy), the blinding of individuals who assessed and
adjudicated study outcomes was felt to be suf cient.
Table 2
Criteria for assigning grades of recommendations for clinical practice
Grade Criteria
Grade A The best evidence was at Level 1
Grade B The best evidence was at Level 2
Grade C The best evidence was at Level 3
Grade D The best evidence was at Level 4 or consensus
G. Booth, A.Y.Y. Cheng / Can J Diabetes 37 (2013) S4eS7 S5
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The degree to which evidence derived from other populations was
felt to be relevant to diabetes also was reected in the wording and
grading of the recommendation. Finally, in the absence of Level 1, 2
or 3 supportingevidence,or if the recommendation wasbased on the
consensus of the Steering and Executive Committees, the highest
grade that could be assigned was D.
Interpreting the Assigned Grade of a Recommendation
The grade assigned to each recommendation is closely linked tothe methodological rigour and robustness of the relevant clinical
research. Therefore, as noted above, a high grade reects a high
degree of condence that following the recommendation will lead
to the desired outcome. Similarly, a lower grade reects weaker
evidence and a greater possibility that the recommendation will
change when more evidence is generated in the future. Of note, the
assigned grade contains no subjective information regarding the
importance of the recommendation or how strongly members of
the committee felt about it; it only contains information regarding
the evidence upon which the recommendation is based. Thus,
many Grade D recommendations were deemed to be very impor-
tant to the contemporary management of diabetes, based on
clinical experience, case series, physiological evidence and current
concepts of disease pathophysiology. However, the paucity of clinical evidence addressing the areas of therapy, prevention,
diagnosis or prognosis precluded the assignment of a higher grade.
Clearly, clinicians need to base clinical decisions on the best
available relevant evidence that addresses clinical situations.
However, they also frequently are faced with having to act in the
absence of clinical evidence, and there are many situations where
good clinical evidence may be impossible, impractical or too
expensive to generate (which implies that it would be impossible to
develop Grade A recommendations). For example, it took
the United Kingdom Prospective Diabetes Study (UKPDS) Group
>20 years to collect and publish Level 1 evidence leading to a Grade
A recommendation in support of the role of tight glycemic control
to reduce microvascular disease in people with type 2 diabetes.
Prior to the publication of the UKPDS results, the recommendationfor glycemic control to prevent microvascular consequences was
a Grade B recommendation (9).
Varying grades of recommendations, therefore, reect varying
degrees of certainty regarding the strength of inference that can be
drawn from the evidence in support of the recommendation.
Therefore, these evidence-based guidelines and their graded
recommendations are designed to satisfy 2 important needs: 1) the
explicit identication of the best research upon which the recom-
mendation is based and an assessment of its scientic relevance
and quality (captured by the assignment of a level of evidence to
each citation); and 2) the explicit assignment of strength of the
recommendation based on this evidence (captured by the grade). In
this way, they provide a convenient summary of the evidence to
facilitate clinicians in the task of “weighting” and incorporatingever increasing evidence into their daily clinical decision making.
They also facilitate the ability of clinicians, healthcare planners,
healthcare providers and society, in general, to critically examine
any recommendation and arrive at their own conclusions regarding
its appropriateness. Thus, these guidelines facilitate their own
scrutiny by others according to the same principles that they use to
scrutinize the literature.
It is important to note that the system chosen for grading
recommendations differs from the approach used in some other
guideline documents, such as the one pertaining to the periodic
health examination in Canada, in which harmful practices were
assigned a grade of D (8). In this Canadian Diabetes Association
guidelines document, recommendation to avoid any harmful
practices would be graded in the same manner as all other
recommendations. However, it should be noted that the authors of
these guidelines focused on clinical practices that were thought to
be potentially benecial and did not seek out evidence regarding
the harmfulness of interventions.
External Peer Review and Independent Methodological
Review
In May 2012, a draft document was circulated nationally and
internationally for review by numerous stakeholders and experts in
relevant elds. This input was then considered by the Executive and
Steering Committees, and revisions were made accordingly.
Subsequently, a panel of 6 methodologists, who were not directly
involved with the initial review and assessment of the evidence,
independently reviewed each recommendation, its assigned grade
and supportive citations. Based on this review, the wording,
assigned level of evidence and grade of each recommendation were
reassessed and modied as necessary. Revised recommendations
were reviewed and approved by the Executive and Steering
Committees. Selected recommendations were presented at a public
forum at the Canadian Diabetes Association/Canadian Society of
Endocrinology and Metabolism Professional Conference and Annual
Meetings in Vancouver, British Columbia, on October 13, 2012.
Disclosure of Duality of Interest
Committee members were volunteers and received no remu-
neration or honoraria for their participation. Members of all
committees signed an annual duality of interest form listing all
nancial interests or relationships with manufacturer(s) of any
commercial product(s) and/or provider(s) of commercial services.
Dualities of interest were discussed during deliberations where
relevant. In the case of a potential duality or outright conict of
interest, committee members removed themselves from discus-
sions. Funding for the development of the guidelines was provided
from the general funds of the Canadian Diabetes Association and
from unrestricted educational grants from Novo Nordisk CanadaInc, Eli Lilly Canada Inc, Merck Canada Inc, Bristol-Myers Squibb
and AstraZeneca, and Novartis Pharmaceuticals Canada Inc. These
companies were not involved in any aspect of guideline develop-
ment, literature interpretation, the decision to publish or any other
aspect related to the publication of these guidelines, and they did
not have access to guideline meetings, guideline drafts or
committee deliberations.
Guideline Updates
A process to update the full guidelines will commence within
5 years and will be published in 2018. Updates to individual
chapters may be published sooner in the event of signicant
changes in evidence supporting the recommendations. The Exec-utive and Steering Committees of the 2013 revision will continue to
remain intact to deliberate any potential updates to individual
chapters until such time as the Executive and Steering Committees
for the 2018 revision have been created.
Other Relevant Guidelines
Introduction, p. S1
References
1. Canadian Diabetes Association Clinical Practice Guideline Expert Committee.Canadian Diabetes Association 2003 clinical practice guidelines for the preven-tion and management of diabetes in Canada. Can J Diabetes 2003;27(suppl 2):S1e152.
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2. Canadian Diabetes Association Clinical Practice Guideline Expert Committee.Canadian Diabetes Association 2008 clinical practice guidelines for theprevention and management of diabetes in Canada. Can J Diabetes 2008;32-(suppl 1):S1e201.
3. Straus SE,McAlisterFA. Whatis theprognosis?In: GersteinHC, Haynes RB,editors.Evidence-based Diabetes Care. Hamilton, ON: BC Decker Inc; 2001. p. 6 e12.
4. American Medical Association. Users’ Guides to the Medical Literature: Essentials of Evidence-based Clinical Practice. Chicago, IL: American Medical Association; 2001.
5. Jaeschke R, Guyatt GH. How should diagnostic tests be chosen and used? In:Gerstein HC, Haynes RB, editors. Evidence-based Diabetes Care. Hamilton, ON:BC Decker Inc; 2001. p. 13e23.
6. Holbrook AM, Clarke J-A, Raymond C, et al. How should a particular problem bemanaged? Incorporating evidence about therapies into practice. In: Gerstein HC,Haynes RB, editors. Evidence-based Diabetes Care. Hamilton, ON: BC Decker Inc;2001. p. 24e47.
7. Harris SB, Webster-Bogaert SM. Evidence-based clinical practice guidelines. In:Gerstein HC, Haynes RB, editors. Evidence-based Diabetes Care. Hamilton, ON:BC Decker Inc; 2001. p. 48e61.
8. Goldbloom R, Battista RN. The periodic health examination: 1. Introduction.CMAJ 1986;134:721e3.
9. Meltzer S, Leiter L, Daneman D, et al. 1998 clinical practice guidelines for themanagement of diabetes in Canada. CMAJ 1998;159(suppl 8):S1e29.
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Clinical Practice Guidelines
Denition, Classication and Diagnosis of Diabetes, Prediabetes
and Metabolic Syndrome
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee
The initial draft of this chapter was prepared by Ronald Goldenberg MD, FRCPC, FACE,Zubin Punthakee MD, MSc, FRCPC
KEY MESSAGES
The chronic hyperglycemia of diabetes is associated with signicant long-
term microvascular and macrovascular complications.
A fasting plasma glucose level of 7.0 mmol/L, a 2-hour plasma glucose
value in a 75 g oral glucose tolerance test of 11.1 mmol/L or a glycated
hemoglobin (A1C) value of 6.5% can predict the development of reti-
nopathy. This permits the diagnosis of diabetes to be made on the basis of
each of these parameters.
Theterm “prediabetes” refers to impaired fasting glucose, impaired glucose
tolerance or an A1C of 6.0% to 6.4%, each of which places individuals at
high risk of developing diabetes and its complications.
Denition of Diabetes and Prediabetes
Diabetes mellitus is a metabolic disorder characterized by the
presence of hyperglycemia due to defective insulin secretion,
defective insulin action or both. The chronic hyperglycemia of
diabetes is associated with relatively specic long-term microvas-
cular complications affecting the eyes, kidneys and nerves, as well
as an increased risk for cardiovascular disease (CVD). Thediagnostic
criteria for diabetes are based on thresholds of glycemia that are
associated with microvascular disease, especially retinopathy.
“Prediabetes” is a practical and convenient term referring to
impaired fasting glucose (IFG), impaired glucose tolerance (IGT) (1)
or a glycated hemoglobin (A1C) of 6.0% to 6.4%, each of which
places individuals at high risk of developing diabetes and its
complications.
Classication of Diabetes
The classication of type 1 diabetes, type 2 diabetes and
gestational diabetes mellitus (GDM) is summarized in Table 1.
Appendix 1 addresses the etiologic classication of diabetes.
Distinguishing between type 1 and type 2 diabetes is important
because management strategies differ, but it may be dif cult at the
time of diagnosis in certain situations. Physical signs of insulin
resistance and autoimmune markers, such as anti-glutamic acid
decarboxylase (GAD) or anti-islet cell antibody (ICA) antibodies,
may be helpful, but have not been adequately studied as diagnostic
tests in this setting. While very low C-peptide levels measured after
months of clinical stabilization may favour type 1 diabetes (2), theyare not helpful in acute hyperglycemia (3). Clinical judgement with
safe management and ongoing follow-up is a prudent approach.
Diagnostic Criteria
Diabetes
The diagnostic criteria for diabetes are summarized in Table 2
(1). These criteria are based on venous samples and laboratory
methods.
A fasting plasma glucose (FPG) level of 7.0 mmol/L correlates
most closely with a 2-hour plasma glucose (2hPG) value of 11.1
mmol/L in a 75 g oral glucose tolerance test (OGTT), and each
predicts the development of retinopathy (5e
11).The relationship between A1C and retinopathy is similar to that
of FPG or 2hPG with a threshold at around 6.5% (5e7,11,12).
Although the diagnosis of diabetes is based on an A1C threshold for
developing microvascular disease, A1C is also a continuous
cardiovascular (CV) risk factor and a better predictor of macro-
vascular events than FPG or 2hPG (13,14). Although many people
identied by A1C as having diabetes will not have diabetes by
traditional glucose criteria and vice versa, there are several
advantages to using A1C for diabetes diagnosis (15). A1C can be
measured at any time of day and is more convenient than FPG
or 2hPG in a 75 g OGTT. A1C testing also avoids the problem of
day-to-day variability of glucose values as it reects the average
plasma glucose (PG) over the previous 2 to 3 months (1).
In order to use A1C as a diagnostic criterion, A1C must bemeasured using a validated assay standardized to the National
Glycohemoglobin Standardization Program-Diabetes Control and
Complications Trial reference. It is important to note that A1C may
be misleading in individuals with various hemoglobinopathies, iron
deciency, hemolytic anaemias, and severe hepatic and renal
disease (16). In addition, studies of various ethnicities indicate that
African Americans, American Indians, Hispanics and Asians have
A1C values that are up to 0.4% higher than those of Caucasian
patients at similar levels of glycemia (17,18). The frequency of
retinopathy begins to increase at lower A1C levels in American
blacks than in American whites, which suggests a lower threshold
for diagnosing diabetes in black persons (19). Research is required
Contents lists available at SciVerse ScienceDirect
Canadian Journal of Diabetesj o u r n a l h o m e p a g e :
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http://dx.doi.org/10.1016/j.jcjd.2013.01.011
Can J Diabetes 37 (2013) S8eS11
http://www.sciencedirect.com/science/journal/14992671http://www.canadianjournalofdiabetes.com/http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://dx.doi.org/10.1016/j.jcjd.2013.01.011http://www.canadianjournalofdiabetes.com/http://www.sciencedirect.com/science/journal/14992671
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to determine if A1C levels differ in African Canadians or Canadian
First Nations. A1C values also are affected by age, rising by up to
0.1% per decade of life (20,21). More studies may help to determine
if age- or ethnic-specic adjusted A1C thresholds are required for
diabetes diagnosis. Also, A1C is not recommended for diagnostic
purposes in children, adolescents, pregnant women or those with
suspected type 1 diabetes.
Thedecision ofwhichtestto usefor diabetesdiagnosis (Table2) is
left to clinical judgement. Each diagnostic test has advantages and
disadvantages (Table 3). In the absence of symptomatic hypergly-
cemia, if a single laboratory test result is in the diabetes range,
a repeat conrmatory laboratory test (FPG,A1C, 2hPG ina 75g OGTT)
must be done on another day. It is preferable that the same test be
repeated (in a timely fashion) for conrmation, but a random PG in
the diabetes range in an asymptomatic individual should be
conrmed with an alternate test. In the case of symptomatic
hyperglycemia,the diagnosishas been made anda conrmatory test
is not required before treatment is initiated. In individuals in
whom type 1 diabetes is likely (younger or lean or symptomatic
hyperglycemia, especially with ketonuria or ketonemia), conrma-
tory testing should not delay initiation of treatment to avoid rapid
deterioration. If results of 2 different tests are available and both are
above the diagnostic cutpoints, the diagnosis of diabetes is
conrmed.Whenthe results ofmorethan1 test are available (among
FPG,A1C,2hPGina75gOGTT)andtheresultsarediscordant,thetest
whose result is above the diagnostic cutpoint should be repeated
and the diagnosis made on the basis of the repeat test.
Prediabetes
The term “prediabetes” refers to IFG, IGT or an A1C of 6.0% to
6.4% (Table 4), each of which places individuals at high risk of developing diabetes and its complications. Not all individuals with
prediabetes will necessarily progress to diabetes. Indeed, a signi-
cant proportion of people who are diagnosed with IFG or IGT will
revert to normoglycemia. People with prediabetes, particularly in
the context of the metabolic syndrome, would benet from CV risk
factor modication.
While people with prediabetes do not have the increased risk
for microvascular disease as seen in diabetes, theyare at risk for the
development of diabetes and CVD (23). IGT is more strongly
associated with CVD outcomes than is IFG. Individuals identied as
having both IFG and IGT are at higher risk for diabetes as well as
CVD. While there is no worldwide consensus on the denition of
IFG (24,25), the Canadian Diabetes Association denes IFG as an
FPG value of 6.1 to 6.9 mmol/L due to the higher risk of developingdiabetes in these individuals compared to dening IFG as an FPG
value of 5.6 to 6.9 mmol/L (25).
While there is a continuum of risk for diabetes in individuals
with A1C levels between 5.5% and 6.4%, population studies
demonstrate that A1C levels of 6.0% to 6.4% are associated with
Table 1
Classication of diabetes (1)
Type 1 diabetes* encompasses diabetes that is primarily a result of
pancreatic beta cell destruction and is prone to ketoacidosis. This form
includes cases due to an autoimmune process and those for which the
etiology of beta cell destruction is unknown.
Type 2 diabetes may range from predominant insulin resistance with
relative insulin deciency to a predominant secretory defect with insulin
resistance.
Gestational diabetes mellitus refers to glucose intolerance
with onset or rst recognition during pregnancy. Other specic types include a wide variety of relatively uncommon
conditions, primarily specic genetically dened forms of diabetes or
diabetes associated with other diseases or drug use (Appendix 1).
* Includes latent autoimmune diabetes in adults (LADA); the term used to
describe the small number of people with apparent type 2 diabetes who appear to
have immune-mediated loss of pancreatic beta cells (4).
Table 2
Diagnosis of diabetes
FPG ‡7.0 mmol/L
Fasting ¼ no caloric intake for at least 8 hours
or
A1C ‡6.5% (in adults)
Using a standardized, validated assay in the absence of factors that affect the
accuracy of the A1C and not for suspected type 1 diabetes (see text)
or
2hPG in a 75 g OGTT ‡11.1 mmol/L
orRandom PG ‡11.1 mmol/L
Random ¼ anytime of theday, without regardto theinterval since thelast meal
In the absence ofsymptomatic hyperglycemia,if a singlelaboratory test resultis
in the diabetes range, a repeat conrmatory laboratory test (FPG, A1C, 2hPG in
a 75 g OGTT) must be done on another day. It is preferable that the same test be
repeated (in a timely fashion) for conrmation, but a random PG in the diabetes
range in an asymptomaticindividual shouldbe conrmed with an alternatetest.
In the case of symptomatic hyperglycemia, the diagnosis has been made and
a conrmatory test is notrequiredbefore treatmentis initiated. In individuals in
whom type 1 diabetes is likely (younger or lean or symptomatic hyperglycemia,
especially with ketonuria or ketonemia), conrmatory testing should not delay
initiation of treatment to avoid rapid deterioration. If results of 2 different tests
are available and both are above the diagnostic cutpoints, the diagnosis of
diabetes is conrmed.
2hPG, 2-hour plasma glucose; A1C , glycated hemoglobin; FPG, fasting plasma
glucose; OGTT , oral glucose tolerance test; PG, plasma glucose.
Table 3
Advantages and disadvantages of diagnostic tests for diabetes* (22)
Parameter Advantages Disadvantages
FPG Established standard
Fast and easy
Single sample
Predicts microvascular
complications
Sample not stable
High day-to-day variability
Inconvenient (fasting)
Reects glucose homeostasis
at a single point in time
2hPG in
a 75 gOGTT
Established standard
Predicts microvascularcomplications
Sample not stable
High day-to-day variability Inconvenient
Unpalatable
Cost
A1C Convenient (measure any
time of day)
Single sample
Predicts microvascular
complications
Better predictor of macro-
vascular disease than FPG
or 2hPG in a 75 g OGTT
Low day-to-day variability
Reects long-term glucose
concentration
Cost
Misleading in various
medical conditions (e.g.
hemoglobinopathies, iron
deciency, hemolytic
anaemia, severe hepatic or
renal disease)
Altered by ethnicity and
aging
Standardized, validated
assay required
Not for diagnostic use in
children, adolescents, preg-
nant women or those withsuspected type 1 diabetes
2hPG, 2-hour plasma glucose; A1C , glycated hemoglobin; FPG, fasting plasma
glucose; OGTT , oral glucose tolerance test.
* Adapted from Sacks D. A1C versus glucose testing: a comparison. Diabetes Care.
2011;34:518e523.
Table 4
Diagnosis of prediabetes
Test Result Prediabetes category
FPG (mmol/L) 6.1e6.9 IFG
2hPG i n a 75 g OGTT ( mm ol /L ) 7.8e11.0 IGT
A1C (%) 6.0e6.4 Prediabetes
2hPG, 2-hour plasma glucose; A1C , glycated hemoglobin; FPG, fasting plasma
glucose; IFG, impaired fasting glucose; IGT , impaired glucose tolerance; OGTT , oral
glucose tolerance test.
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a higher risk for diabetes compared to levels between 5.5% and 6.0%
(26). While the American Diabetes Association denes prediabetes
as an A1C between 5.7% and 6.4%, the Canadian Diabetes Associa-
tion has based the denition on a higher risk group and includes an
A1C of 6.0% to 6.4% as a diagnostic criterion for prediabetes (1).
However, A1C levels below 6.0% can indeed be associated with an
increased risk for diabetes (26). The combination of an FPG of 6.1 to
6.9 mmol/L and an A1C of 6.0% to 6.4% is predictive of 100%
progression to type 2 diabetes over a 5-year period (27).
Metabolic syndrome
Prediabetes and type 2 diabetes are often manifestations of
a much broader underlying disorder (28), including the metabolic
syndromeda highly prevalent, multifaceted condition charac-
terized by a constellation of abnormalities that include abdominal
obesity, hypertension, dyslipidemia and elevated blood glucose.
Individuals with the metabolic syndrome are at signicant risk of
developing CVD. While metabolic syndrome and type 2 diabetes
often coexist, those with metabolic syndrome without diabetes
are at signicant risk of developing diabetes. Evidence exists to
support an aggressive approach to identifying and treating
people, not only those with hyperglycemia but also those with
the associated CV risk factors that make up the metabolic
syndrome, such as hypertension, dyslipidemia and abdominal
obesity, in the hope of signicantly reducing CV morbidity and
mortality.
Various diagnostic criteria for the metabolic syndrome have
been proposed. In 2009, a harmonized denition of the metabolic
syndrome was established, with at least 3 or more criteria required
for diagnosis (Table 5) (29).
Other Relevant Guidelines
Screening for Type 1 and Type 2 Diabetes, p. S12
Reducing the Risk of Developing Diabetes, p. S16
Type 1 Diabetes in Children and Adolescents, p. S153
Type 2 Diabetes in Children and Adolescents, p. S163
Relevant Appendix
Appendix 1. Etiologic Classication of Diabetes Mellitus
References
1. American Diabetes Association. Diagnosis and classication of diabetesmellitus. Diabetes Care 2012;35(suppl 1):S64e71.
2. Patel P, Macerollo A. Diabetes mellitus: diagnosis and screening. Am FamPhysician 2010;81:863e70.
3. Unger RH, Grundy S. Hyperglycemia as an inducer as well as a consequence of impaired islet cell function and insulin resistance: implications for themanagement of diabetes. Diabetologia 1985;28:119e21.
4. Turner R, Stratton I, Horton V, et al. UKPDS 25: autoantibodies to islet-cellcytoplasm and glutamic acid decarboxylase for prediction of insulin require-ment in type 2 diabetes. UK Prospective Diabetes Study Group. Lancet 1997;350:1288e93.
5. McCance DR, Hanson RL, Charles MA, et al. Comparison of tests for glycatedhemoglobin and fasting and two hour plasma glucose concentrations asdiagnostic methods for diabetes. BMJ 1994;308:1323e8.
6. Engelgau MM, Thompson TJ, Herman WH, et al. Comparison of fasting and2-hour glucose and HbA1c levels for diagnosing diabetes. Diagnostic criteriaand performance revisited. Diabetes Care 1997;20:785e91.
7. The Expert Committee on the Diagnosis and Classication of Diabetes Mellitus.Report of the expert committee on the diagnosis and classication of diabetesmellitus. Diabetes Care 1997;20:1183e97.
RECOMMENDATIONS
1. Diabetes should be diagnosed by any of the following criteria:
FPG 7.0 mmol/L [Grade B, Level 2 (11)] A1C 6.5% (for use in adults in the absence of factors that affect the
accuracy of A1C and not for use in those with suspected type 1 dia-
betes) [Grade B, Level 2 (11)]
2hPG in a 75 g OGTT 11.1 mmol/L [Grade B, Level 2 (11)]
Random PG 11.1 mmol/L [Grade D, Consensus]
2. In the absence of symptomatic hyperglycemia, if a single laboratory test
result is in the diabetes range, a repeat conrmatory laboratory test (FPG,
A1C, 2hPG in a 75 g OGTT) must be done on another day. It is preferable
that the same test be repeated (in a timely fashion) for conrmation, but
a random PG in the diabetes range in an asymptomatic individual should
be conrmed with an alternate test. In the case of symptomatic hyper-
glycemia, the diagnosis has been made and a conrmatory test is not
required before treatment is initiated. In individuals in whom type 1
diabetes is likely (younger or lean or symptomatic hyperglycemia, espe-
cially with ketonuria or ketonemia), conrmatory testing should not delay
initiation of treatment to avoid rapid deterioration. If results of twodifferent tests are available and both are above the diagnostic cutpoints,
the diagnosis of diabetes is conrmed [Grade D, Consensus].
3. Prediabetes (dened as a state which places individuals at high risk of
developing diabetes and its complications) is diagnosed by any of the
following criteria:
IFG (FPG 6.1e6.9 mmol/L) [Grade A, Level 1 (23)]
IGT (2hPG in a 75 g OGTT 7.8e11.0 mmol/L) [Grade A, Level 1 (23)]
A1C 6.0%e6.4% (for usein adults in theabsence of factorsthat affect the
accuracy of A1C and not for use in suspected type 1 diabetes) [Grade B,
Level 2 (26)].
Abbreviations:
2hPG, 2-hour plasma glucose; A1C , glycated hemoglobin; FPG, fasting
plasma glucose; IFG, impaired fasting glucose; IGT , impaired glucose
tolerance; OGTT , oral glucose tolerance test; PG, plasma glucose.
Table 5
Harmonized denition of the metabolic syndrome: 3 measures to make the diagnosis of metabolic syndrome* (29)
Measure Categorical cutpoints
Men Women
Elevated waist circumference (population- and country-specic cutpoints):
Canada, United States
Europid, Middle Eastern, sub-Saharan African, Mediterranean
Asian, Japanese, South and Central American
102 cm
94 cm
90 cm
88 cm
80 cm
80 cm
Elevated TG (drug treatment for elevated TG is an alternate indicator y) 1.7 mmol/L
Reduced HDL-C (drug treatment for reduced HDL-C is an alternate indicator
y
) <
1.0 mmol/L in males,
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8. Ito C, Maeda R, Ishida S, et al. Importance of OGTT for diagnosing diabetesmellitus based on prevalence and incidence of retinopathy. Diabetes Res ClinPract 2000;49:181e6.
9. Miyazaki M, Kubo M, Kiyohara Y, et al. Comparison of diagnostic methods fordiabetes mellitus based on prevalence of retinopathy in a Japanese population:the Hisayama Study. Diabetologia 2004;47:1411e5.
10. Tapp RJ, Zimmett PZ, Harper CA, et al. Diagnostic thresholds for diabetes: theassociation of retinopathy and albuminuria with glycaemia. Diabetes Res ClinPract 2006;73:315e21.
11. The DETECT-2 Collaboration Writing Group. Glycemic thresholds for diabetesspecic retinopathy. Diabetes Care 2011;34:145e50.
12. International Expert Committee. International Expert Committee report on therole of the A1C assay in the diagnosis of diabetes. Diabetes Care 2009;32:1327e34.
13. Sarwar N, Aspelund T, Eiriksdottir G, et al. Markers of dysglycaemia and risk of coronary heart disease in people without diabetes: Reykjavik ProspectiveStudy and systematic review. PLoS Med 2010;7:e1000278.
14. Selvin E, Steffes MW, Zhu H, et al. Glycated hemoglobin, diabetes,and cardiovascular risk in nondiabetic adults. N Engl J Med 2010;362:800e11.
15. Report of a World Health Organization Consultation. Use of glycatedhaemoglobin (HbA1C) in the diagnosis of diabetes mellitus. Diabetes Res ClinPract 2011;93:299e309.
16. Gallagher EJ, Bloomgarden ZT, Roith D. Review of hemoglobin A1c in themanagement of diabetes. J Diabetes 2009;1:9e17.
17. Herman WH, Ma Y, Uwaifo G, et al. Differences in A1C by race and ethnicityamong patients with impaired glucose tolerance in the Diabetes PreventionProgram. Diabetes Care 2007;30:2453e7.
18. Ziemer DC, Kolm P, Weintraub WS, et al. Glucose-independent, black-white differences in hemoglobin A1c levels. Ann Intern Med 2010;152:
770e
7.
19. Tsugawa Y, Mukamal K, Davis R, et al. Should the HbA1c diagnostic cutoff differbetween blacks and whites? A cross-sectional study. Ann Intern Med 2012;157:153e9.
20. Davidson MB, Schriger DL. Effect of age and race/ethnicity on HbA1c levels inpeople without known diabetes mellitus: implications for the diagnosis of diabetes. Diabetes Res Clin Pract 2010;87:415e21.
21. Pani L, Korenda L, Meigs JB, Driver C, Chamany S, Fox CS, et al. Effect of agingon A1C levels in persons without diabetes: evidence from the FraminghamOffspring Study and NHANES 2001-2004. Diabetes Care 2008;31:1991e6.
22. Sacks D. A1C versus glucose testing: a comparison. Diabetes Care 2011;34:518e23.
23. Santaguida PL, Balion C, Morrison K, et al. Diagnosis, prognosis, and treatment of impairedglucose tolerance and impairedfasting glucose.Evidence report/technologyassessment no. 128. Agency Healthcare Research and Quality Publication No05-E026-2. Rockville, MD: Agency for Healthcare Research and Quality; September2005.
24. Shaw JE,Zimmet PZ,Alberti KG.Point: impaired fastingglucose:the case forthenew American Diabetes Association criterion. Diabetes Care 2006;29:1170e2.
25. Forouhi NG, Balkau B, Borch-Johnsen K, et al, EDEG. The threshold fordiagnosing impaired fasting glucose: a position statement by the EuropeanDiabetes Epidemiology Group. Diabetologia 2006;49:822e7.
26. Zhang X, Gregg E, Williamson D, et al. A1C level and future risk of diabetes:a systematic review. Diabetes Care 2010;33:1665e73.
27. Heianza Y, Arase Y, Fujihara K, et al. Screening for pre-diabetes to predict futurediabetes usingvarious cut-off points forHbA1c and impaired fastingglucose: theToranomon Hospital Health Management Center Study 4 (TOPICS 4). DiabeticMed 2012;29:e279e85.
28. Reaven GM. Banting Lecture 1988. Role of insulin resistance in human disease.Diabetes 1988;37:1595e607.
29. Alberti KGMM, Eckel R, Grundy S, et al. Harmonizing the metabolic syndrome.
Circulation 2009;120:1640e
5.
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Clinical Practice Guidelines
Screening for Type 1 and Type 2 Diabetes
Canadian Diabetes Association Clinical Practice Guidelines Expert Committee
The initial draft of this chapter was prepared by Jean-Marie Ekoé MD, CSPQ, PD,Zubin Punthakee MD, MSc, FRCPC, Thomas Ransom MD, MSc, FRCPC,Ally P.H. Prebtani BScPhm, MD, FRCPC, Ronald Goldenberg MD, FRCPC, FACE
KEY MESSAGES
In the absence of evidence for interventions to prevent or delay type 1
diabetes, screening for type 1 diabetes is not recommended.
Screening for type 2 diabetes using a fasting plasma glucose (FPG) and/or
glycated hemoglobin (A1C) should be performed every 3 years in indi-
viduals40 yearsof ageor in individualsat high risk usinga risk calculator.
Diabetes will be diagnosed if A1C is 6.5% (see Denition, Classication
and Diagnosis chapter, p. S8).
Testing with a 2-hour plasma glucose (2hPG) in a 75 g oral glucose
tolerance test (OGTT) should be undertaken in individuals with an FPG of
6.1e6.9 mmol/Land/or an A1Cof 6.0%e6.4% in order to identify individuals
with impaired glucose tolerance (IGT) or diabetes.
Testing with a 2hPG in a 75 g OGTT may be undertaken in individuals with
anFPG5.6e6.0mmol/L and/orA1C 5.5%e5.9% and1 riskfactorin order to
identify individuals with IGT or diabetes.
The clinical spectrum of diabetes ranges from a low-risk to
a higher-risk individual or to the symptomatic patient who needs
immediate treatment. Screening for diabetes implies testing for
diabetes in individuals without symptoms who are unaware of
their condition. Screening for diabetes will also detect individuals
at increased risk for diabetes (prediabetes) or individuals with less
severe states of dysglycemia who may still be at risk for type 2
diabetes. Screening strategies vary according to the type of diabetes
and evidence of effective interventions to prevent progression of
prediabetes to diabetes and/or reduce the risk of complications
associated with diabetes. The growing importance of diabetes
screening is undeniable (1).
In contrast to other diseases, there is no distinction between
screening and diagnostic testing. Therefore, to screen for diabetesand prediabetes, the same tests would be used as for diagnosis
of both medical conditions (see Denition, Classication and
Diagnosis chapter, p. S8).
Screening for Type 1 Diabetes
Type1 diabetes mellitus is primarily a resultof pancreatic beta cell
destruction due to an immune-mediated process that is likely incited
by environmental factors in genetically predisposed individuals. An
individual’s risk of developing type 1 diabetes can be estimated by
considering family history of type 1 diabetes with attention to age of
onset and sex of the affected family members (2) and proling
immunity and genetic markers (3). The loss of pancreatic beta cells in
the development of type 1 diabetes passes through a subclinicalprodrome that can be detected reliably in rst- and second-degree
relatives of persons with type 1 diabetes by the presence of pancre-
atic islet autoantibodies in their sera (4). However, in a recent large
study, one-time screening for glutamic acid decarboxylaseantibodies
(GADAs) and islet antigen-2 antibodies (IA-2As) in the general
childhood population in Finland would identify 60% of those indi-
vidualswho willdeveloptype 1 diabetes over thenext27 years.Initial
positivity for GADAs and/or IA-2As had a sensitivity of 61% (95%
condence interval [CI] 36e83%) for type 1 diabetes. The combined
positivity for GADAs and IA-2As had both a specicity and a positive
predictive value of 100% (95% CI 59e100%) (5). Ongoing clinical
studies are testing different strategies for preventing or reversing
early type1 diabetes in the presence of positive autoimmunity.Given
that the various serological markers are not universally available andin theabsence of evidence for interventionsto prevent or delay type1
diabetes, no widespread recommendations for screening for type 1
diabetes can be made.
Screening for Type 2 Diabetes
Adults
Undiagnosed type 2 diabetes may occur in >2.8% of the general
adult population (6), and the number increases to >10% in some
populations (7,8). Tests for hyperglycemia can identify these
individuals, many of whom will have, or will be at risk for,
preventable diabetes complications (5,6). To be effective,
population-based screening would have to involve wide coverageand would have the goal of early identication and subsequent
intervention to reduce morbidity and mortality. Using various
multistaged screening strategies, the ADDITION-Europe study
showed that 20% to 94% of e