Low leptin but high insulin resistance of smokers in Japanese men

Aims: To investigate the association between smoking and leptin, and to discuss their influence on diabetes in a large-scale study of Japanese men. Methods: A cross-sectional study was carried out in 2002. The subjects were 2836 men aged 35-66. Smoking history was investigated in a self-administered questionnaire. Blood leptin, glucose and insulin were measured. Results: Significant differences in leptin levels and homeostasis model assessment of insulin resistance (HOMA-IR) related to smoking status were observed (P = 0.001 and P = 0.008, respectively). The multivariate-adjusted geometric means of leptin in current, past and never smokers were 3.88, 4.08 and 4.12 ng/ml, respectively, while the means of HOMA-IR were 1.64, 1.61 and 1.49, respectively. The age-, body mass index-, and other lifestyle-adjusted prevalences of diabetes in current and never smokers were 9.2 and 4.7%, respectively. That of current smokers was significantly higher than in never smokers (P < 0.001). The dose-dependent association found between the intensity of smoking and leptin levels in current smokers was statistically significant (P = 0.030). Conclusions: The present finding may explain in part an association among smoking, leptin levels and diabetes. Smoking is one of the important modifiable risk factors for the prevention of diabetes. (C) 2008 Elsevier Ireland Ltd. All rights reserved.