Substitution of Carbohydrates for Fats and Risk of Type 2 Diabetes among Korean Middle-Aged Adults: Findings from the Korean Genome and Epidemiology Study

Using data from a 16 year follow-up cohort of the Korean Genome Epidemiology Study, this study assessed the effects of carbohydrate intake on incident diabetes, including replacement of fats or proteins with carbohydrates. In addition, this study evaluated modification effects based on 24 genetic variants associated with type 2 diabetes. For the daily intake of macronutrients, the energy-adjusted intake and percentage of total energy intake were calculated. The effects were assessed using a Cox proportional hazards model; results were presented as hazard ratios with 95% confidence intervals (CIs). Among the 7413 participants considered to be diabetes-free at baseline, 1193 individuals were considered to have incident diabetes. The risk of incident diabetes was found to be high at both extremes of carbohydrate intake, with the lowest risk at 78 E%. The replacement of 5 E% intake from fats with isocaloric carbohydrates showed an 11% increase in the risk of diabetes (95% CI: 1.01–1.21), which was significant in men, participants >50 years of age, and participants with a high educational level. Regarding gene–environment interactions, the relationship between carbohydrate intake and incident diabetes was not dependent on genetic variants. A nonlinear relationship was observed between carbohydrate intake and incident diabetes. The substitution of carbohydrates for fats was also associated with an increased risk of incident diabetes.