[Gender difference in association between smoking and metabolic risks among community adults]

Cigarette smoking is a risk factor for the development of insulin resistance. However, whether a smoker has a lesser waist circumference (WC) and whether the potential changes in WC may reduce the benefits of smoking cessation remains in dispute. The aims of this study are to re-examines the relationships between smoking and metabolic risk factors by the data from Beijing adults.

A total of 3710 men and 6344 women, aged 18 - 92 years old, were sampled from community centers in Beijing for this cross-sectional clinical study between April and August 2007. Their concentrations of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C) and plasma glucose (PG) were measured. And the anthropometric parameters (WC, body weight and height) and blood pressure (BP) were record according to a standard protocol. Their social, demographic, personal medical history and behavioral characteristics were collected by the well-trained staff. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. The relationships between smoking and metabolic syndrome were analyzed by χ(2) test and logistic regression.

The mean age and glucose concentration were similar in both genders. Males tended to have a higher mean BP (systolic and diastolic), a higher level of TG and a lower HDL-C. Among the obesity indices, the mean WC was higher in males than that in females whereas the mean BMI higher in females. The means of BMI and WC were 24.99 kg/m(2) and 89.13 cm for males and 25.49 kg/m(2) and 85.49 cm for females respectively. Smoking was an independent risk factor of metabolic syndrome in male subjects. It was mainly due to a higher prevalence of dyslipidemia, i.e. a higher level of TG and a lower level of HDL-C in smokers. And the trough prevalence of central obesity was higher in former smokers than current smokers. With adjustment for age, alcohol intake, and regular physical activity, the odds ratios [OR (95%CI)] of never smokers, ex-smokers, and current smokers were 1.00, 1.10 (0.92 - 1.47), and 1.36 (1.02 - 1.69) for hypertriglyceridemia (P < 0.05) and 1.00, 1.08 (0.79 - 1.32), and 1.59 (1.13 - 1.89) for low HDL-C respectively (P < 0.05). The odds ratios of the MS were 1.00 (referent), 1.10 (0.76 - 1.43), and 1.49 (1.06 - 1.89) for never smokers, ex-smokers, and current smokers respectively (P < 0.05). Cessation of smoking had a general trend of lowering the risk of metabolic syndrome in a year-dependent manner in males. In females, the prevalence of metabolic syndrome and obesity was similar between smokers and nonsmokers. Among the features of metabolic syndrome, only a low HDL-C was associated with chronic smoking in females.

Although smokers tend to have a lower waist circumference than nonsmokers, the males have higher risk factors for metabolic disorders. There is no significant relationship between smoking and metabolic syndrome in female subjects.