Background – Medical nutrition therapy for the management of type 2 diabetes (T2DM) is focussed on weight, glycaemic control and plasma lipids. Higher protein diets, when compared to high carbohydrate, low fat diets, may be beneficial for weight loss; effects on plasma lipids is variable. High protein diets, because weight and glycaemic control are related, may also result in improved glycaemic control.
Objectives – To compare and contrast a higher protein (HP) diet with a high carbohydrate (HC) diet in free-living people with T2DM.
Design – One year, randomised trial of HP vs HC nutrition education given by a dietitian in three sessions over a period of three months. At baseline, 12 weeks and one year anthropometric measurements were taken; three-day weighed food records and blood samples for biochemical analyses were collected; questionnaires relating to exercise and quality of life were completed. Participants’ food preferences were defined at the start of the study.
Outcomes – 123 subjects randomised to either HC (n=61) or HP (n=62) group. All values are least squares means ± 95% confidence interval of the least squares means. Weight was significantly (p=0.001) lower at one year compared to baseline for participants consuming the HC diet (88.4 ± 4.3 kg vs 86.8 ± 4.3 kg) and significantly (p<0.001) lower for participants consuming the HP diet (87.5 ± 4.3 kg vs 85.7 ± 4.3 kg). Lipids improved in both groups but there was no change in glycaemic control. There was no difference between groups. Participants in the HP group did not follow the advice to eat a HP diet.
Conclusion – Neither the HC nor the HP diet proved superior in the management of people with T2DM. The study suggests that it is more difficult for people to follow advice to eat a HP diet compared to a HC diet. However, it may suit some motivated individual patients and it may help them to lose more weight, but implementation at a mass level appears impractical.