Background:Diabetes mellitus (DM) remains a major health problem worldwide.Several clinical trials have shown the superiority of the Traditional Chinese Medicine in delaying or reversing the development and progression of DM.This study aimed to evaluate the efficacy of Jinlida (JLD) granule,a Chinese herbal recipe,in the treatment of impaired glucose tolerance (IGT) and its effect on the prevention of DM.Methods:Sixty-five IGT patients were randomized to receive one bag of JLD granules three times daily (JLD group,n =34) or no drug intervention (control group,n =31) for 12 weeks.Oral glucose tolerance test,glycated hemoglobin A1c (HbA1c),body mass index,blood lipids levels,fasting insulin,and insulin resistance calculated using homeostatic model assessment (HOMA-IR) of all the patients were observed and compared before and after the treatment.Results:Sixty-one participants completed the trial (32 in JLD group and 29 in the control group).There were statistically significant decreases in HbA1c (P ＜ 0.001),2-h plasma glucose (P ＜ 0.001),and HOMA-IR (P =0.029) in JLD group compared with the control group after 12 weeks of treatment.After 12 weeks of treatment,two (6.9％) patients reted to normal blood glucose,and five (17.2％) patients ted into DM in control group,while in the JLD group,14 (43.8％) reted to normal blood glucose and 2 (6.2％) ted into DM.There was a significant difference in the number of subjects who had normal glucose at the end of the study between two groups (P =0.001).Conclusions:JLD granule effectively improved glucose control,increased the conversion of IGT to normal glucose,and improved the insulin resistance in patients with IGT.This Chinese herbal medicine may have a clinical value for IGT.