The association of dietary macronutrients composition with the incidence of type 2 diabetes, using iso-energetic substitution models: Tehran Lipid and Glucose Study

There is still controversy on optimal percentage of macronutrient intakes especially carbohydrate on prevention of type 2 diabetes (T2D). The aim of the current study was to evaluate the iso-energetic substitution of dietary macronutrients in relation to incidence of T2D.This prospective study was conducted on 6547 subjects who were followed for 3.0 ± 1.6 years. Dietary intakes were evaluated using a valid and reliable semi-quantitative food frequency questionnaire. Biochemical variables and anthropometrics were evaluated at baseline and follow-up examinations. Multivariate Cox proportional hazard regression models were used to estimate the hazards ratio (HR) of T2D.A one unit higher proportion of carbohydrate from whole grain at the expense of carbohydrate from non-whole grain (HR = 0.82, 95% CI = 0.71-0.95), protein (HR = 0.75, 95% CI = 0.60-0.94), total fat (HR = 0.79, 95% CI = 0.67-0.93), saturated fatty acid (HR = 0.79, 95% CI = 0.65-0.96), poly-unsaturated fatty acid (HR = 0.81, 95% CI = 0.68-0.96) and mono-unsaturated fatty acid (HR = 0.75, 95% CI = 0.60-0.94) was associated with decreased risk of T2D. The substitution of protein and fats was not associated with diabetes. Risk of T2D increased from quartiles 1-4 for trans-fatty acid (HR: 1.00, 1.27, 0.95, 1.97, Ptrend = 0.01).A higher proportion of carbohydrate from whole grain in replacement of refined grain, and other macronutrients was associated with decreased risk of T2D. Also our study suggests a positive association between trans-fatty acid intake and risk of T2D.