Relationship between smoking and metabolic syndrome in men with diabetes mellitus

Metabolic syndrome is a potent risk factor for cardiovascular disease and is often complicated in patients with diabetes. The aim of this study was to determine whether and how smoking is related to metabolic syndrome in patients with diabetes.

Subjects were men with diabetes (n=2675) who had been diagnosed as a result of health examinations at their workplaces. They were divided into nonsmokers, light smokers (≤ 20 cigarettes per day) and heavy smokers (>20 cigarettes per day). The relationships of smoking with metabolic syndrome and its components, including obesity, high blood pressure, and dyslipidemia [high triglycerides and/or low high-density lipoprotein cholesterol (HDL-C)] in nondrinkers, light drinkers (<22 grams of ethanol per day), and heavy drinkers (≥ 22 grams of ethanol per day) were investigated by logistic regression analysis with adjustment for age, regular exercise, and drug therapy for diabetes.

In nondrinkers with diabetes, the odds ratio (OR) versus nonsmokers for metabolic syndrome was significantly higher in heavy smokers (2.47 [95% confidence interval (CI) 1.43-4.25]) but not different in light smokers [1.03 (95% CI 0.71-1.49)] when compared with the reference level of 1.00. In the light and heavy drinker groups, the ORs versus nonsmokers for metabolic syndrome were not significantly different from the reference level in the smoker groups, except for a significantly lower OR of light smokers in the heavy drinker group [0.69 (95% CI 0.53-0.90)]. In nondrinkers, the ORs of heavy smokers versus nonsmokers for large waist circumference [1.64 (95% CI 1.01-2.68)], high triglycerides [1.78 (95% CI 1.12-2.81)], and low HDL-C [3.20 (95% CI 1.99-5.14]), but not the OR for high blood pressure [1.02 (95% CI 0.60-1.72)], were significantly higher than the reference level.

In nondrinkers with diabetes, there is a positive association between heavy smoking and metabolic syndrome, which is mainly due to higher risks of central obesity and dyslipidemia, such as hypertriglyceridemia and low HDL cholesterolemia, in heavy smokers than in nonsmokers.