Abstract: Objective: To investigate the relation between plasma homocysteine（Hcy） and insulin resistance（IR） and islet beta cell function in individuals with different glucose tolerance. Methods: A total 83 subjects were recruited by oral glucose tolerance test（OGTT） in this study.Of these 83 subjects,32 had normal glucose tolerence（NGT）,24 had impaired glucose tolerance（IGT） and 27 had newly diagnosed type 2 diabetes mellitus（DM）.Levels of glucose and insulin were measured at fasting and 2h post-prandial.Plasma Hcy levels were measured by polarization immunoassay（FPIA）. Results: Fasting plasma Hcy concentrations were significantly higher in IGT and DM groups in NGT group（P＜0.01）.Fasting plasma Hcy concentrations were higher in IGT group than in DM group,with no significant difference between the two groups（P＞0.05）.Fasting insulin levels were significantly higher in IGT group than in NGT and DM groups（P＜0.01）.HOMA-IR was lower in NGT group than in IGT and DM groups（P＜0.01）.The insulin sensitive index of NGT group was higher than that of DM group（P＜0.01）.HBCI,HBCI/IR and FBCI/IR were significantly higher in NGT group than in IGT and DM groups（P＜0.01）.HOMA-IR was positively correlated with plasma Hcy.ISI was negatively correlated with Hcy.HBCI/IR and FBCI/IR were negatively correlated with plasma Hcy. Conclusion: Concentration of Hcy is higher in patients with IGT and DM than in those with NGT.Beta cell function is more severely impaired in patients with IGT and DM than in those with NGT.