Background There are studies suggesting smoking may increase the risk of type 2 diabetes.Effects of smoking oninsulin secretion and insulin resistance(IR)are,however,controversial.Methods This is a cross-sectional study.Since there were very few smokers among Hong Kong Chinese women,onlymen(n=1068)were analyzed in this report.Fasting and 2-hour plasma glucose and insulin were measured.Insulinogenicindex as well as beta-cell function and IR based on homeostatic model assessment(HOMA)by computer model(HOMACalculator v2.2)were calculated.Results Of the 1068 men,147 had newly diagnosed diabetes,131 newly diagnosed impaired glucose tolerance(IGT)and 790 were non-diabetic normal controls.Smokers had similar fasting and 2-hour insulin levels,insulinogenic indexand HOMA derived beta-cell function as compared to non-smokers in the groups with diabetes,IGT or normal oralglucose tolerance test(OGTT).IR was also similar between smokers,ex-smokers and non-smokers in those with normalOGTT.In men with IGT or diabetes,after adjustment for age and body mass index,smokers were more insulin resistantas compared to non-smokers(IR,IGT:1.59±1.07 vs 1.03±0.54,P<0.05;diabetes:1.96±1.36 vs 1.06±0.45,P<0.01).WithLogistic regression analysis,comparing smokers and non-smokers,IR was independently associated with smoking(oddsratio(95% CI),IGT:2.23(1.05,4.71);diabetes:3.92(1.22,12.58)).None of the other insulin parameters enter into themodel among those with normal OGTT or comparing ex-smokers and non-smoker or smokers and ex-smokers.Conclusions In Chinese men,smoking did not show any direct association with insulin levels and pancreatic insulinsecretion.Smoking men with IGT or diabetes appeared more insulin resistant than their non-smoking counterparts. Background There are studies suggesting smoking may increase the risk of type 2 diabetes. Effects of smoking oninsulin secretion and insulin resistance (IR) are, however, controversial. Methods This is a cross-sectional study .ince there were very few smokers among Hong Kong Chinese women, onlymen (n = 1068) were analyzed in this report. Fasting and 2-hour plasma glucose and insulin were measured. Insulingenicindex as well as beta-cell function and IR based on homeostatic model assessment (HOMA) by computer model v2.2) were calculated. Results of the 1068 men, 147 had newly diagnosed diabetes, 131 newly diagnosed impaired glucose tolerance (IGT) and 790 were non-diabetic normal controls. Simkers had similar fasting and 2-hour insulin levels, insulinogenic index and HOMA derived beta-cell function as compared to non-smokers in the groups with diabetes, IGT or normal oral glucose tolerance test (OGTT). IR was also similar between smokers, ex-smokers and non-smokers in those with normalOGTT. Men wit h IGT or diabetes, after adjustment for age and body mass index, smokers were more insulin resistant as compared to non-smokers (IR, IGT: 1.59 ± 1.07 vs 1.03 ± 0.54, P <0.05; diabetes: 1.96 ± 1.36 vs 1.06 ± 0.45 , P <0.01) .With Logistic regression analysis, comparing smokers and non-smokers, IR was independently associated with smoking (oddsratio (95% CI), IGT: 2.23 (1.05,4.71); diabetes: 3.92 (1.22,12.58)). None of the other insulin parameters enter into themodel among those with normal OGTT or comparing ex-smokers and non-smoker or smokers and ex-smokers. Conclusions In Chinese men, smoking did not show any direct association with insulin levels and pancreatic insulin secretion. men with IGT or diabetes had more insulin resistant than their non-smoking counterparts.