Alcohol consumption and the incidence of type 2 diabetes - A 20-year follow-up of the Finnish Twin Cohort Study

OBJECTIVE - The aim of this study was to. investigate alcohol consumption in relation to the incidence of type 2 diabetes. RESEARCH DESIGN AND METHODS - The study population consisted of 22 778, twins of the Finnish Twin Cohort. This cohort was compiled in 1975 and includes all same-sexed twins born in Finland before 1958. Information on alcohol, smoking, diet, physical activity, medical, and social conditions was obtained by questionnaires administered in 1975, 1981, and I 1990. By record linkage to national registers of hospital discharge and prescribed medication, 580 incident cases of type 2 diabetes were identified during 20 years of follow-up. RESULTS - Moderate alcohol consumption (5-29.9 g/day in men and 5-19.9 g/day in women) tended to be associated with a reduced incidence of type 2 diabetes compared with low consumption (<5 g/day). The estimates were lower in overweight (BMI greater than or equal to 25.0 kg/m(2)) subjects (relative risk 0.7, 95% Cl 0.5-1.0 [men]; 0.6, 0.3-1.1 [women]). High alcohol consumption ( greater than or equal to20 g/day) was associated with an increased incidence of type 2 diabetes in lean women (2.9, 1.1-7.5) but not in overweight women or in men. In women, binge drinking was associated with an increased incidence of type 2 diabetes (2.1, 1.0-4.4). Analyses of alcohol-discordant twin pairs supported a reduced risk in moderate consuming twins compared with their low-consuming cotwins (odds ratio 0.5, 95% Cl 0.2-1.5). CONCLUSIONS - The results of this study suggested that moderate alcohol consumption may reduce the risk of type 2 diabetes. On the other hand, binge drinking and high alcohol consumption may increase the risk of type 2 diabetes in women.