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

Summary 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). Conclus