Impact of cigarette smoking on the incidence of Type 2 diabetes mellitus in middle-aged Japanese men: the Osaka Health Survey

Aims To assess the impact of cigarette smoking on the incidence of Type 2 d iabetes mellitus (DM) in middle-aged Japanese men. Methods The study enrolled 6250 men aged 35-60 years and free of diabetes, impaired fasting glucose and hypertension at entry. Type 2 DM was defined b y a fasting plasma glucose level greater than or equal to 7.0 mmol/l or phy sician-diagnosed Type 2 DM. Results Four hundred and fifty cases of Type 2 DM were confirmed during the 60904 person-years follow-up. After adjustment for multiple covariates, in cluding age, body mass index, alcohol consumption, physical activity, paren tal history of diabetes and the level of fasting plasma glucose, total chol esterol, triglycerides, high-density lipoprotein cholesterol and haematocri t, the relative risk of Type 2 DM among current smokers compared with nonsm okers was 1.47 (95% confidence interval (CI) 1.14-1.92). Men who smoked > 3 0 cigarettes/day had a multivariate-relative risk of 1.73 (95% CI 1.20-2.48 ) compared with non-smokers. The number of cigarettes smoked daily and the pack-year values were positively related to the development of Type 2DM in a dose-dependent manner (P for trends = 0.0026 and 0.001, respectively). Conclusions A cigarette smoking habit is an independent risk factor for Typ e 2 DM.