Dietary Inflammatory and Insulinemic Potential and Risk of Type 2 Diabetes: Results from Three Prospective U.S. Cohort Studies

Objective: To examine whether proinflammatory and hyperinsulinemic diets are associated with increased risk of type 2 diabetes.

Research Design and Methods: We prospectively followed 74,767 women from the Nurses’ Health Study (1984-2016), 90,786 women from the Nurses’ Health Study 2 (1989-2017), and 39,442 men from the Health Professionals Follow-up Study (1986-2016). Using repeated measures of food frequency questionnaires, we calculated empirical dietary inflammatory pattern (EDIP) and empirical dietary index for hyperinsulinemia (EDIH) scores which are food-based indices that characterize dietary inflammatory or insulinemic potential based on circulating biomarkers of inflammation or C-peptide. Diagnoses of type 2 diabetes were confirmed by validated supplementary questionnaires.

Results: We documented 19,666 incident type 2 diabetes cases over 4.9 million person-years of follow-up. In the pooled multivariable-adjusted analyses, individuals in the highest EDIP or EDIH quintile had 3.11 times (95% CI, 2.96-3.27) and 3.40 times (95% CI, 3.23-3.58) higher type 2 diabetes risk, respectively, compared to those in the lowest quintile. Additional adjustment for body mass index (BMI) attenuated the associations (Hazard ratio, 1.95; 95% CI, 1.85-2.05 for EDIP; Hazard ratio, 1.87; 95% CI, 1.78-1.98 for EDIH), suggesting adiposity partly mediates the observed associations. Moreover, individuals in both highest EDIP and EDIH quintiles had 2.34 times higher type 2 diabetes risk (95% CI, 2.17-2.52), compared to those in both lowest quintiles, after adjustment for BMI.

Conclusions: Higher dietary inflammatory and insulinemic potential were associated with an increased type 2 diabetes incidence. Findings suggest that inflammation and hyperinsulinemia are potential mechanisms linking dietary patterns and type 2 diabetes development.