Alcohol consumption and incidence of type 2 diabetes. Results from the CoLaus study

Background and aims: Moderate alcohol consumption has been shown to decrease the risk of type 2 diabetes (T2DM), but whether this association is also valid for impaired fasting glucose (IFG) is less well known. We aimed at assessing the impact of alcohol consumption and of type of alcoholic beverage on the incidence of T2DM and T2DM+IFG. Methods and results: As many as 4765 participants (2613 women, mean age 51.7±10.5 years) without T2DM at baseline and followed for an average of 5.5 years. The association between alcohol consumption, type of alcoholic beverage and outcomes was assessed after adjustment for a validated T2DM risk score. During follow-up 284 participants developed T2DM and 643 developed IFG. On bivariate analysis, alcohol consumption was positively associated with the risk of developing T2DM or T2DM+IFG. Moderate (14-27units/week) alcohol consumption tended to be associated with a lower risk of T2DM, but no protective effect was found for T2DM+IFG. Multivariable-adjusted odds ratio (OR) and (95% confidence interval) for T2DM: 0.89 (0.65-1.22), 0.66 (0.42-1.03) and 1.63 (0.93-2.84) for 1-13, 14-27 and 28+units/week, respectively (p for quadratic trend<0.005). For T2DM+IFG, the corresponding ORs were 1.09 (0.90-1.32), 1.33 (1.02-1.74) and 1.54 (0.99-2.39), respectively, p for trend=0.03. No specific effect of alcoholic beverage (wine, beer or spirits) was found for T2DM or for T2DM+IFG. Conclusion: Moderate alcohol consumption is associated with a reduced risk of developing T2DM, but not of developing T2DM+IFG. No specific effect of type of alcoholic beverage was found.