Abstract： Objective To observe the efficacy of rosiglitazone treatment in impaired glucose tolerance (IGT) with hyperinsulinemia. Methods 56 IGT patients were divided into two groups randomly:control group (28 cases) and rosiglitazone group (28 cases). Improving life style were given to control group,while improving life style and rosiglitazone (4mg/d) were given to rosiglitazone group for 12 weeks. The body mass index (BMI),fasting and postprandial plasma glucose,insulin and insulin sensitivity index (ISI) were observed. Results In control group the fasting and postprandial plasma glucose and insulin showed no difference between pre-and post-treatment (P>0.05).The levels of the fasting and postprandial plasma glucose and insulin dropped obviously in rosiglitazone group compared to both the baseline levels and the levels of control group at 12 weeks of treatment(P<0.05). The BMI and body weight dropped obviously in control group at 12 weeks of treatment (all P<0.05),but showed no difference in rosiglitazone group (P>0.05). The ISI increased markedly in rosiglitazone group (P<0.05),but showed no difference in control group (P>0.05). Conclusions The rosiglitazone treatment increases insulin sensitivity obviously,improves first-phase insulin secretion,and postpones the progression to T2DM from impaired glucose tolerance in patients with IGT