diet and exercise for new-onset type 2 diabetes
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www.thelancet.com Vol 378 July 9, 2011 101
Diet and exercise for new-onset type 2 diabetes?
The global burden of diabetes is increasing rapidly. The
International Diabetes Federation reports1 that the
disease affects at least 285 million people worldwide, a
figure that will increase to 438 million by the year 2030.
Each year, roughly 6 million people worldwide develop
diabetes; the vast majority (>90%) have type 2 diabetes.
The increasing prevalence of obesity—fuelled by
excessive calorie intake, suboptimum dietary quality,
and sedentary lifestyles—is driving this epidemic.2
Several large, randomised clinical trials have shown
that intensive lifestyle intervention is highly effective
in prevention of type 2 diabetes among patients with
impaired glucose tolerance, and benefits have been
sustained for several years, even after the end of the
active intervention.3–5 Intensive lifestyle intervention
can also lead to sustained weight loss and a significant
improvement in glycaemic control and fitness in
individuals with pre-existing diabetes.6
An appropriate question is whether less-intensive
lifestyle intervention is beneficial in managing new-
onset type 2 diabetes. In The Lancet, Robert Andrews
and colleagues7 report the Early ACTID (Early ACTivity
In Diabetes) trial. It examined the benefits of dietary
intervention versus diet plus physical activity for
glycaemic control and other metabolic factors among
patients with newly diagnosed diabetes. This 52-week,
multicentre trial had three groups: usual care (control
group, initial dietary consultation and follow-up
every 6 months), diet only (dietary consultation every
3 months with monthly nurse support), and diet plus
activity (as diet group, plus 30 min brisk walking five
times a week); patients were assigned to the groups
in a ratio of two:five:five (99 usual care, 248 diet
only, and 246 diet plus activity). Because the primary
comparison was diet plus activity versus diet only, with
only a secondary interest in usual care, an unequal
randomisation ratio was justified. At 6 months, glycated
haemoglobin A1c (HbA1c) was 0·28% lower in the diet
only intervention group than in the usual care group
compared with a 0·33% difference between the diet
plus activity group and the usual care group, but the
difference between the intervention groups was not
significant. These benefits were slightly attenuated but
remained significant at 12 months. Compared with
controls, patients in both the diet and diet and activity
groups had significant improvements in the secondary
outcomes of weight, waist circumference, and insulin
resistance at both 6 months and 12 months, and use
of hypoglycaemic medication at 12 months. However,
there was no evidence of further benefits from addition
of physical activity to dietary intervention.
These findings should be interpreted in the context of
the trial, which was undertaken in general practices in
the southwest of England, where patients with newly
diagnosed type 2 diabetes are routinely provided with
a standard health education programme on diabetes
management that focuses on dietary advice. Therefore,
the investigators set out to test whether more-intensive
dietary counselling improved glycaemic control and
other outcomes compared with the standard pro-
gramme, and whether additional activity counselling
further improved these outcomes over and above the
dietary programme. The results suggest that given the
same amount of time, advice on diet only had similar
effects over 12 months to combined diet and activity
counselling. The researchers argue that, although more
intensive dietary advice improved outcomes compared
with usual care, there is no justification to add a physical
activity component on top of the dietary programme to
manage newly diagnosed diabetes.
Why was there no further improvement of outcomes
with addition of physical activity to dietary counselling?
Participants were advised to achieve more than 30 min
of brisk walking on at least 5 days per week; data from
Published Online
June 25, 2011
DOI:10.1016/S0140-
6736(11)60692-2
See Articles page 129
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Comment
102 www.thelancet.com Vol 378 July 9, 2011
pedometers showed very good adherence. Previous
clinical trials have shown that increased physical activity,
including brisk walking, significantly improves glycaemic
control among patients with pre-existing diabetes.8
A combination of aerobic exercise and resistance
training, in particular, is more beneficial than aerobic
exercise or resistance training alone.9 The Early ACTID
trial did not include a group assigned only physical
activity; therefore, the results do not necessarily mean
that an increase in physical activity is ineffective for
diabetes management. It is possible that modification
of two complex behaviours at the same time is no more
effective than a change in one—ie, the need for effort in
both aspects of life diminishes positive dietary changes
by patients in the diet plus activity group. Nonetheless,
in subgroup analyses, a combination of diet and exercise
worked significantly better than diet only in participants
with higher HbA1c, insulin resistance, and body-mass
index at baseline.
Another question is whether the improvement in
outcomes is clinically significant. At 6 months, diet
alone improved HbA1c by 0·28% versus 0·33% with
diet and exercise, from a mean baseline value of 6·7%.
The differences are slight but clinically meaningful;
a decrease in HbA1c of 1% (about 11 mmol/mol) can
reduce rates of major cardiovascular disease events
by 12% to 16% and microvascular complications
by 37%.10 Moreover, diet and physical activity can exert
long-term health benefits beyond improvement of
metabolic markers.11 The reduction in HbA1c through
diet and exercise in the Early ACTID study was
comparable to the effect of sitagliptin phosphate and
metformin hydrochloride among patients who had
received no previous treatment for type 2 diabetes.12
In a subset of 381 patients with baseline HbA1c of less
than 7%, HbA1c decreased by 0·20% with sitagliptin
and 0·25% with metformin.
Translation of these results into community settings
requires concerted efforts by patients, dietitians, and
clinicians. In the Early ACTID study, the enhanced dietary
programme included 6·5 h of individual counselling
throughout the year (2 h with a dietitian and 4·5 h with
a nurse). In comparison, the Look AHEAD6 participants
in the intensive lifestyle intervention group met with
dietitians, behavioural counsellors, or exercise specialists
every week for the first 6 months, and three times per
month for the next 6 months. The long-term effects
and cost-effectiveness of these programmes need to
be assessed in future studies. There is little doubt that
improved nutrition and physical activity are beneficial
for individuals with or without diabetes, and research
into the most effective way to deliver these benefits
(including individual behavioural changes and creation
of a supportive food and social environment) deserves
high priority.
Frank B HuDepartment of Nutrition and Department of Epidemiology,
Harvard School of Public Health, Boston, MA 02115, USA
I have received grants or have grants pending from Merck and the California
Walnut Commission, and I have been paid for lectures from Nutrition Impact,
Unilever, and the Institute of Food Technologists.
1 International Diabetes Federation. Diabetes atlas. Epidemiology andmorbidity. 2011. http://www.diabetesatlas.org/content/epidemiology-and-morbidity (accessed April 6, 2011).
2 Schulze MB, Hu FB. Primary prevention of diabetes: what can be done andhow much can be prevented? Annu Rev Public Health 2005; 26: 445–67.
3 Li G, Zhang P, Wang J, et al. The long-term effect of lifestyle interventionsto prevent diabetes in the China Da Qing Diabetes Prevention Study:a 20-year follow-up study. Lancet 2008; 371: 1783–89.
4 Knowler WC, Fowler SE, Hamman RF, et al, for the Diabetes PreventionProgram Research Group. 10-year follow-up of diabetes incidence andweight loss in the Diabetes Prevention Program Outcomes Study.Lancet 2009; 374: 1677–86.
5 Lindström J, Ilanne-Parikka P, Peltonen M, et al, for the Finnish DiabetesPrevention Study Group. Sustained reduction in the incidence of type 2diabetes by lifestyle intervention: follow-up of the Finnish DiabetesPrevention Study. Lancet 2006; 368: 1673–79.
6 Look AHEAD Research Group. Long-term effects of a lifestyle interventionon weight and cardiovascular risk factors in individuals with type 2diabetes mellitus: four-year results of the Look AHEAD trial. Arch Intern Med 2010; 170: 1566–75.
7 Andrews RC, Cooper AR, Montgomery AA, et al. Diet or diet plus physicalactivity versus usual care in patients with newly diagnosed type 2 diabetes:the Early ACTID randomised controlled trial.Lancet 2011; published online June 25. DOI:10.1016/S0140-6736(11)60442-X.
8 Snowling NJ, Hopkins WG. Effects of different modes of exercise trainingon glucose control and risk factors for complications in type 2 diabeticpatients: a meta-analysis. Diabetes Care 2006; 29: 2518–27.
9 Church TS, Blair SN, Cocreham S, et al. Effects of aerobic and resistancetraining on hemoglobin A1c levels in patients with type 2 diabetes:a randomized controlled trial. JAMA 2010; 304: 2253–62.
10 Stratton IM, Adler AI, Neil HA, et al. Association of glycaemia withmacrovascular and microvascular complications of type 2 diabetes(UKPDS 35): prospective observational study. BMJ 2000; 321: 405–12.
11 van Dam RM, Li T, Spiegelman D, Franco OH, Hu FB. Combined impactof lifestyle factors on mortality: prospective cohort study in US women.BMJ 2008; 337: a1440.
12 Aschner P, Katzeff HL, Guo H, et al. Effi cacy and safety of monotherapyof sitagliptin compared with metformin in patients with type 2 diabetes.Diabetes Obes Metab 2010, 12: 252–61.