A prospective study of cigarette smoking and the incidence of diabetes mellitus among US male physicians

PURPOSE: To determine the association between cigarette smoking and the inc idence of type 2 diabetes mellitus. SUBJECTS AND METHODS: We studied 21,068 US male physicians aged 40 to 84 ye ars in the Physicians' Health Study who were initially free of diagnosed di abetes mellitus, cardiovascular disease, and cancer. Information about ciga rette smoking and other risk indicators was obtained at baseline. The prima ry outcome was reported diagnosis of type 2 diabetes mellitus. RESULTS: During 255,830 person-years of follow-up, 770 new cases of type 2 diabetes mellitus were identified. Smokers had a dose-dependent increased r isk of developing type 2 diabetes mellitus: compared with never smokers, th e age-adjusted relative risk was 2.1 (95% confidence interval [CI]: 1.7 to 2.6) for current smokers of greater than or equal to 20 cigarettes per day, 1.4 (95% CT: 1.0 to 2.0) for current smokers of <20 cigarettes per day, an d 1.2 (95% CI: 1.0 to 1.4) for past smokers. After multivariate adjustment for body mass index, physical activity, and other risk factors, the relativ e risks were 1.7 (95% CI: 1.3 to 2.3) for current smokers of <greater than or equal to>20 cigarettes per day, 1.5 (95% CI: 1.0 to 2.2) for current smo kers of <20 cigarettes per day, and 1.1 (95% CI: 1.0 to 1.4) for past smoke rs. Total pack-years of cigarette smoking was also associated with the risk of type 2 diabetes mellitus (P for trend <0.001). CONCLUSIONS: These prospective data support the hypothesis that cigarette s moking is an independent and modifiable determinant of type 2 diabetes mell itus. Am J Med. 2000;109: 538-542. (C) 2000 by Excerpta Medica, Inc.