Abstract: To investigate the curative effect of Metformin on patients with type 2 diabetes mellitus (T2DM) and impaired glucose tolerance (IGT). MethodsPlasma glucose, HbA1c, blood lipid, blood pressure, body mass index (BMI), waist hip ratio (WHR), uric acid (UA), plasma adiponectin and visfatin levels were detected in 30 cases of T2DM or IGT and 30 healthy subjects. The T2DM group and IGT groups were given a rational diet and appropriate exercises while 1?500?mg/d metformin was administrated lasting for 1 year. Changes of the above indexes before and after treatment were detected. Plasma adiponectin and visfatin levels were assayed by ELISA. Blood total cholesterol(TC), triglyceride, highdensity lipoprotein cholesterol(HDLc), lowdensity lipoprotein cholesterol(LDLc), and UA were detected by automatic biochemical apparatus. Fasting plasma glucose (FPG) and 2?h plasma glucose (2hPG) were assayed by the glucose oxidase method. HbA1c was determined by the high pressure lipid phase method. ResultsCompared with the controls, BMI, TC, FPG, 2hPG and HbA1c were significantly higher in T2DM and IGT patients（P＜0.01 or P＜0.05）, while adiponectin and visfatin levels were significantly lower（P＜0.01, P＜0.05）. In the IGT group, BMI, WHR, LDLc, TC, FPG, and 2hPG were significantly reduced after treatment（P＜0.01 or P＜0.05）. In the T2DM group, BMI, WHR, TC, FPG, 2HPG, and HbA1c were also significantly lower than