A randomized behavioural trial targeting glycaemic index improves dietary, weight and metabolic outcomes in patients with type 2 diabetes

Abstract

Objective: Glycaemic index (GI) reflects the postprandial glucose response of carbohydrate-containing foods. A diet with lower GI may improve glycaemic control in people with diabetes. The purpose of the present study was to evaluate the change in outcomes following a behavioural intervention which promoted lower-GI foods among adults with diabetes.

Design: A pre-test-post-test control group design was used with participants randomly assigned to an immediate (experimental) or delayed (control) treatment group. The intervention included a 9-week, group-based intervention about carbohydrate and the glycaemic index. Dietary, anthropometric and metabolic measures were obtained pre/post-intervention in both groups and at 18-week follow-up for the immediate group.

Setting: The study was conducted in a rural community in the north-eastern USA.

Subjects: Adults having type 2 diabetes mellitus for > or =1 year, aged 40-70 years and not requiring insulin therapy (n 109) were recruited.

Results: Following the intervention, mean dietary GI (P < 0.001), percentage of energy from total fat (P < 0.01) and total dietary fibre (P < 0.01) improved in the immediate compared with the delayed group. Mean BMI (P < 0.0001), fasting plasma glucose (P = 0.03), postprandial glucose (P = 0.02), fructosamine (P = 0.02) and insulin sensitivity factor (P = 0.04) also improved in the immediate group compared with the delayed group. Mean waist circumference among males (P < 0.01) and body weight among males and females (P < 0.01) were significantly different between treatment groups.

Conclusions: Educating clients about carbohydrate and the glycaemic index can improve dietary intake and health outcomes among adults with type 2 diabetes.