A behavioural intervention incorporating specific glycaemic index goals improves dietary quality, weight control and glycaemic control in adults with type 2 diabetes

Objective A lower glycaemic index (GI) diet is associated with a reduction in glycosylated Hb (HbA1c) in people with diabetes. Yet, little research has been conducted to determine the effects of specific goals regarding consumption of low GI (LGI) foods on diabetes outcomes. The present study evaluated a behavioural intervention on dietary intake, weight status and HbA1c, which included a goal to consume either six or eight servings of LGI foods daily.Design A parallel two-group design was used. Following the 5-week intervention, participants were randomly assigned to the group of six (n 15) or eight (n 20) servings of LGI foods daily and followed up for 8 weeks. Dietary intake was assessed using the mean of 4 d food records.Setting A metropolitan community in the USA.Subjects Individuals aged 40-65 years with type 2 diabetes of ≥1 year and HbA1c ≥ 7·0 % were eligible.Results There was no significant difference between goal difficulty groups with regard to GI servings at the end of the study. However, mean consumption of LGI foods increased by 2·05 (se 0·47) and 1·65 (se 0·40) servings per 4184 kJ in the six (P < 0·001) and eight (P < 0·001) LGI serving groups, respectively. For all participants combined, there were significant decreases in mean HbA1c (-0·58 (se 0·21) %; P = 0·01), weight (-2·30 (se 0·78) kg; P = 0·01), BMI (-0·80 (se 0·29) kg/m²; P = 0·01) and waist circumference (-2·36 (se 0·81) cm; P = 0·01).Conclusions An intervention including a specific goal to consume six to eight servings of LGI foods daily can improve diabetes outcomes. Clinicians should help patients set specific targets for dietary change and identify ways of achieving those goals.