Joint association of glycemic load and alcohol intake with type 2 diabetes incidence in women

Background: Little is known about the joint association between glycemic index (GI), glycemic load (GL), and alcohol intake with type 2 diabetes (T2D). Objective: The objective of this study was to examine whether alcohol intake alters the associations between carbohydrate quality (GI) or quality and quantity (GL) and T2D incidence in women. Design: Participants from the Nurses' Health Study who were free of T2D, cardiovascular disease, or cancer (n = 81,827) at baseline in 1980 were followed for 26 y. Cumulative averages of GI, GL, total carbohydrates, and alcohol intake were calculated every 2-4 y from validated food-frequency questionnaires. Cox proportional hazard models were used to adjust for covariates. Results: We documented 6950 cases of T2D during follow-up. After adjustment for lifestyle and dietary factors, the positive association between GL and T2D risk was attenuated in subjects with higher alcohol intakes. RRs that compared the top and bottom quintiles of GL were 1.29 (95% CI: 1.11, 1.49; P-trend < 0.001) in women with alcohol intakes of 0 to <5 g/d, 1.34 (95% CI: 0.93, 1.92; P-trend = 0.05) in women with alcohol intakes of 5 to <15 g/d, and 0.99 (95% CI: 0.60, 1.65; P-trend = 0.82) in women with alcohol intakes ≥15 g/d (P-interaction = 0.02). However, a higher intake of alcohol did not modify the positive association between GI and T2D (P-interaction = 0.76). Conclusion: Our findings suggest that a higher alcohol intake (≥15 g/d) attenuates the positive association between GL and T2D incidence.