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 11<middle dot>8 years (IQR 9<middle dot>0-13<middle dot>0), 7326 (5<middle dot>7%) 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 1<middle dot>15 [95% CI 1<middle dot>03-1<middle dot>29]). 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 1<middle dot>21, 95% CI 1<middle dot>06-1<middle dot>37). The glycaemic index was more strongly associated with diabetes among individuals with a higher BMI (quintile 5 vs quintile 1; HR 1<middle dot>23 [95% CI 1<middle dot>08-1<middle dot>41]) than those with a lower BMI (quintile 5 vs quintile 1; 1<middle dot>10 [0<middle dot>87-1<middle dot>39]; p interaction=0<middle dot>030). 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.