Associations of the Glycaemic Index and the Glycaemic Load with Risk of Type 2 Diabetes in 127 594 People from 20 Countries (PURE): a Prospective Cohort Study

Background The association between the glycaemic index and the glycaemic load with type 2 diabetes incidence is controversial. We aimed to evaluate this association in an international cohort with diverse glycaemic index and glycaemic load diets. Methods The PURE study is a prospective cohort study of 127 594 adults aged 35-70 years from 20 high -income, middle -income, and low-income countries. Diet was assessed at baseline using country -specific validated food frequency questionnaires. The glycaemic index and the glycaemic load were estimated on the basis of the intake of seven categories of carbohydrate -containing foods. Participants were categorised into quintiles of glycaemic index and glycaemic load. The primary outcome was incident type 2 diabetes. Multivariable Cox Frailty models with random intercepts for study centre were used to calculate hazard ratios (HRs). Findings During a median follow-up of 118 years (IQR 90-130), 7326 (57%) incident cases of type 2 diabetes occurred. In multivariable adjusted analyses, a diet with a higher glycaemic index was significantly associated with a higher risk of diabetes (quintile 5 vs quintile 1; HR 115 [95% CI 103-129]). Participants in the highest quintile of the glycaemic load had a higher risk of incident type 2 diabetes compared with those in the lowest quintile (HR 121, 95% CI 106-137). The glycaemic index was more strongly associated with diabetes among individuals with a higher BMI (quintile 5 vs quintile 1; HR 123 [95% CI 108-141]) than those with a lower BMI (quintile 5 vs quintile 1; 110 [087-139]; p interaction=0030). Interpretation Diets with a high glycaemic index and a high glycaemic load were associated with a higher risk of incident type 2 diabetes in a multinational cohort spanning five continents. Our findings suggest that consuming low glycaemic index and low glycaemic load diets might prevent the development of type 2 diabetes.