In type 2 diabetes, randomisation to advice to follow a low-carbohydrate diet transiently improves glycaemic

control compared with advice to follow a low-fat diet producing a

similar weight loss.

Guldbrand H et al Diabetologia. 2012 May 6. [Open access]

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Pronutritionist’s background

• In recent meta-analyses low carbohydrate diets have been either equally effective or better than low fat diets in the treatment of type 2 diabetes (Kirk et al. 2008, Kodama et al. 2009)

• The trials included in these meta-analyses have been short, ie. shorter than 1 year

• In non-diabetic subjects low carbohydrate diets have either been equally effective or outperformed low fat diets, when minimum 2 year trials are considered (Shai et al. 2008, Sacks et al. 2009, Foster et al. 2010, Cardillo et al. 2006)

• The long terms effects on low carbohydate diets on cardiovascular risk factors, glucose and insulin parameters and weight in diabetes are not known

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Methods (patients)• Randomized trial, parallell groups, 2 years

• Primary outcomes: weight, HbA1c

• Secondary outcomes: LDL, HDL, triglyserides, blood pressure• N=61, type 2 diabetics (BMI 33), free living subjects∼• Diets were to provide 1600 kcal for females or 1800 kcal for males

(design was not ad libitum)• Diets

– Carbohydrates 20 E %, ie. Low carbohydrate diet. No restriction on the use of saturated fat was given

– Carbohydrates 55-60 E %, ie. Low fat diet. The diet followed the Swedish dietary guidelines for diabetics at time of commencement of the trial and saturated fat was to be stricted to the level of 10 E %

• Primary care setting, dietitians provided information on diets in group meetings which took place 4 times (at baseline, 2, 4 and 12 months)

• No food was provided for free• Insulin, incretin mimetics and oral diabetes drugs were allowed

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Methods (schematic)

Randomization (ballots)

20 % of energy as carbohydrates, ie. low carb diet

55-60 of energy as carbohydrates ie, low fat diet

2 years

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Results (macronutrients)

Dietary intakes (based on food diaries)

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Data are given for all participants who provided complete diet recordsaCompared with baselinebFor change over all time pointscFor change over all time points (between groups)dDenotes statistically significant difference between changes in the two groupseDenotes statistically significant difference between groups at baseline

Results (fats)

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Data are given for all participants who provided complete diet recordsaCompared with baselinebFor change over all time pointscFor change over all time points (between groups)dDenotes statistically significant difference between changes in the two groupseDenotes statistically significant difference between groups at baseline

Dietary intakes (based on food diaries)

Dietary intakes (based on food diaries)

Results (weight)

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The weight reduction did not differ between the groups (p = 0.33 for all time points)

Low carb diet

Low fat diet

Results (HbA1c)

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The reduction in HbA1c level was statistically significant within the low-carbohydrate group (p = 0.005 for all time points), but did not differ between the groups when compared at all time points (p = 0.76). To convert values for HbA1c in mmol/mol into %, divide by 10.929 and add 2.15

Low fat diet

Low carb diet

Results (lipids and blood pressure)

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Data are given for all participants who provided complete diet recordsaCompared with baselinebFor change over all time pointscFor change over all time points (between groups)dDenotes statistically significant difference between changes in the two groupseDenotes statistically significant difference between groups at baseline

Guldbrand H et al Diabetologia. 2012 May 6

Results for only those patients who consumed ≤6,694 kJ/day (1,600 kcal/day) for women or ≤7,531 kJ/day (1,800 kcal/day) for men according to the last diet record at 24 months; 17 patients in the low-fat group and 18 patients in the low-carbohydrate group.

Results (diverse)

• No patients were lost during the follow up, all were analysed

• 7 patients did not attend all group sessions (3 low carb and 4 in low fat group)

• HDL-cholesterol increased by 33% in patients reasonably compliant with low carb diet (post hoc analysis)

• Average insulin dose at 6 months was lower in low carb diet group (p = 0,046)

• There were no other significant changes in drug usage

• In neither group the target carbohydrate intake was reached, ie ≤ 20 E % and 55-60 E %

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Pronutritionist’s discussion (1/2)

• Both diets induced similar weight reductions

• HDL –cholesterol was increased in low carbohydrate diet at all time points. No other significant differences in lipids between groups were found in spite of radical difference in macronutrient composition of diets

• LDL-cholesterol did not change in either of the groups, even if the intake of saturated fat was increased in low carbohydrate group from 16 E % to 19 E %

• It is noteworthy that absolute intake fat did not change in low carb (high fat) group

• Low carbohydrate tended to induce bigger energy deficit than low fat diet, but the difference between the groups was not significant

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Pronutritionist’s discussion (2/2)

• The study shows that a long term low carbohydrate diet in type 2 diabetes may not reap all the benefits demonstrated in shorter trials

• The study shows that there may not be any metabolic risks in type 2 diabetes related to low carbohydrate diet in spite of the increased intake of saturated fat

• The incidence of gastrointestinal side effects was not monitored and remain unknown in diabetes

• The trial has a high clinical relevance because it was run with usual resources at health care centres in Nordic countries

• This study suggests that low fat and low carbohydrate diets are equally effective and metabolically beneficial. The choice between the diets might be done on individual preference

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Please read the whole paper at

Guldbrand H et al Diabetologia. 2012 May 6.

[Open access]

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11/04/23

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Reijo Laatikainen, Authorized Nutritionist, MBA

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