Aims To assess the impact of cigarette smoking on the incidence of Type 2 diabetes 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 by a fasting plasma glucose level ≥ 7.0 mmol/l or physician-diagnosed Type 2 DM.
Results Four hundred and fifty cases of Type 2 DM were confirmed during the 60 904 person-years follow-up. After adjustment for multiple covariates, including age, body mass index, alcohol consumption, physical activity, parental history of diabetes and the level of fasting plasma glucose, total cholesterol, triglycerides, high-density lipoprotein cholesterol and haematocrit, the relative risk of Type 2 DM among current smokers compared with non-smokers was 1.47 (95% confidence interval (CI) 1.14–1.92). Men who smoked > 30 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 2 DM 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 Type 2 DM.