Alcohol as a risk factor for type 2 diabetes: A systematic review and meta-analysis

OBJECTIVE - To clarify the dose-response relationship between alcohol consumption and type 2 diabetes. RESEARCH DESIGN AND METHODS - A systematic computer-assisted and hand search was conducted to identify relevant articles with longitudinal design and quantitative measurement of alcohol consumption. Adjustment was made for the sick-quitter effect. We used fractional polynomials in a meta-regression to determine the dose-response relationships by sex and end point using lifetime abstainers as the reference group. RESULTS - The search revealed 20 cohort studies that met our inclusion criteria. A U-shaped relationship was found for both sexes. Compared with lifetime abstainers, the relative risk (RR) for type 2 diabetes among men was most protective when consuming 22 g/day alcohol (RR 0.87 [95% CI 0.76 -1.00]) and became deleterious at just over 60 g/day alcohol (1.01 [0.71-1.44]). Among women, consumption of 24 g/day alcohol was most protective (0.60 [0.52- 0.69]) and became deleterious at about 50 g/day alcohol (1.02 [0.83-1.26]). CONCLUSIONS - Our analysis confirms previous research findings that moderate alcohol consumption is protective for type 2 diabetes in men and women.