Alcohol Intake, Drinking Pattern, and Risk of Type 2 Diabetes in Three Prospective Cohorts of U.S. Women and Men

OBJECTIVE: Although the adverse effects of excessive alcohol consumption are well established, the association between light to moderate alcohol consumption (≤30 g ethanol per day) and risk of type 2 diabetes (T2D) remains controversial and holds substantial public health implications. We aimed to examine the association of total alcohol intake and drinking pattern with T2D among three cohorts, Nurses' Health Study (NHS), Nurses' Health Study II (NHSII), and Health Professionals Follow-up Study (HPFS). RESEARCH DESIGN AND METHODS: Former regular drinkers were excluded from baseline nondrinkers. Hazard ratios (HRs) and 95% CIs were estimated by Cox models. RESULTS: Over 3 decades of follow-up, 20,551 T2D cases were documented among 200,969 participants. In total alcohol intake analyses, alcohol consumption was associated with a lower risk of T2D, with either nondrinkers or 0.1-4.9 g/day as the reference. The association was robust to extended latency periods and alternative modeling of exposure. Higher drinking frequency was associated with a lower T2D risk. For example, compared with drinking 1-2 days per week, the HRs (95% CIs) for drinking 5-6 days were 0.73 (0.65, 0.83), 0.73 (0.62, 0.86), and 0.76 (0.67, 0.86) in the NHS, NHSII, and HPFS cohorts, respectively. When modeled jointly, the lower risk of T2D among drinkers was primarily driven by the drinking frequency. The inverse association began at drinking 1-2 days per week in women and 3-4 days per week in men and was strongest for ≥5 days per week, regardless of drinking <10 g or ≥30 g per drinking day. CONCLUSIONS: Light to moderate alcohol consumption, especially regular light drinking, was associated with a lower risk of T2D in both men and women.