Objectives: To investigate whether smoking and the smoking status are predictors of the incident impaired fasting glucose (IFG) or type 2 diabetes in Korean men.
Methods: A cohort of 1,717 Korean men without IFG or diabetes, who underwent annual periodic health examinations for 4 years (2002-2006), were retrospectively investigated. IFG and diabetes were defined as a serum fasting glucose concentration of 100-125 mg/dL and more than 126 mg/dL, respectively. Cox's proportional hazards model was used to evaluate the association between smoking and development of IFG or type 2 diabetes.
Results: A total of 558 cases (32.5%) of incident IFG and 50 cases (2.9%) of diabetes occurred. After controlling for the potential predictors of diabetes, the relative risk for IFG, compared with the never smokers, was 1.02 (95% CI=0.88 to 1.19) for the ever-smokers, 0.96 (95% CI=0.79-1.16) for those who smoked 1-9 cigarettes/d, 1.15 (95% CI=1.01 to 1.30) for those who smoked 10-19 cigarettes/d, and 1.31 (95% CI=1.10 to 1.57) for those who smoked 20 or more cigarettes/d (the P value for the current smokers was only p<0.002). The respective multivariate adjusted relative risks for type 2 diabetes, compared with the never-smokers, were 1.07 (95% CI=0.64 to 1.92), 1.47 (95% CI=0.71 to 3.04), 1.84 (95% CI=0.92-3.04), and 1.87 (95% CI=1.13-3.67), respectively (the P value for the current smokers was only p=0.004).
Conclusions: The smoking status and the number of cigarettes smoked daily are associated with an increased risk for developing IFG or type 2 diabetes in Korean men.