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

Abstract

Aims/hypothesis: The study aimed to compare the effects of a 2 year intervention with a low-fat diet (LFD) or a lowcarbohydrate diet (LCD), based on four group meetings to achieve compliance. Methods: This was a prospective randomised parallel trial involving 61 adults with type 2 diabetes consecutively recruited in primary care and randomised by drawing ballots. Patients that did not speak Swedish could not be recruited. The primary outcomes in this non-blinded study were weight and HbA1c. Patients on the LFD aimed for 55-60 energy per cent (E%) and those on LCD for 20 E% from carbohydrate. Results The mean BMI and HbA1c of the participants were 32.7±5.4 kg/m2 and 57.0±9.2 mmol/mol, respectively. No patients were lost to follow-up. Weight loss did not differ between groups and was maximal at 6 months: LFD -3.99± 4.1 kg (n=31); LCD -4.31±3.6 kg (n030); p<0.001 within groups. At 24 months, patients on the LFD had lost -2.97± 4.9 kg and those on LCD -2.34±5.1 kg compared with baseline (p=0.002 and p=0.020 within groups, respectively). HbA1c fell in the LCD group only (LCD at 6 months -4.8± 8.3 mmol/mol, p=0.004, at 12 months -2.2±7.7 mmol/mol, p=0.12; LFD at 6 months -0.9±8.8 mmol/mol, p=0.56). At 6 months, HDL-cholesterol had increased with the LCD (from 1.13±0.33 mmol/l to 1.25±0.47 mmol/l, p=0.018) while LDL-cholesterol did not differ between groups. Insulin doses were reduced in the LCD group (0 months, LCD 42±65 E, LFD 39±51 E; 6 months, LCD 30±47 E, LFD 38±48 E; p=0.046 for between-group change). Conclusions/interpretation: Weight changes did not differ between the diet groups, while insulin doses were reduced significantly more with the LCD at 6 months, when compliance was good. Thus, aiming for 20% of energy intake from carbohydrates is safe with respect to cardiovascular risk compared with the traditional LFD and this approach could constitute a treatment alternative. © The Author(s) 2012.