Smoking and incidence of diabetes among U.S. adults: findings from the Insulin Resistance Atherosclerosis Study.

OBJECTIVE The objective of this study was to determine the association between smoking and incident diabetes among U.S. adults. RESEARCH DESIGN AND METHODS The Insulin Resistance Atherosclerosis Study (IRAS) was a prospective study of the associations of insulin sensitivity and cardiovascular risk factors. We examined the relationship between smoking status categories (never, former, and current) and incident 5-year type 2 diabetes among 906 participants free of diabetes at baseline. We also considered the effect of pack-year categories (never, former <20 pack-years, former > or = 20 pack-years, current <20 pack-years, and current > or = 20 pack-years) upon diabetes incidence. RESULTS Of current smokers, 96 (25%) developed diabetes at 5 years, compared with 60 (14%) never smokers. After multivariable adjustment, current smokers exhibited increased incidence of diabetes compared with never smokers (odds ratio [OR] 2.66, P = 0.001). Similar results were found among current smokers with > or = 20 pack-years with normal glucose tolerance (5.66, P = 0.001). CONCLUSIONS Smoking shares a robust association with incident diabetes, supporting the current Surgeon General's warnings against cigarette smoking.