To identify a safe and effective Impaired Glucose Tolerance (IGT) intervention program using Traditional Chinese Medicine (TCM) supported by Standard Health Care Advice (SHCA) for the evidence-based TCM intervention in IGT and evidence-based prevention of type 2 diabetes. A total of 510 IGT patients were randomly assigned into either control or TCM intervention group (255 patients for each group). The control group received standard health care according to SHCA. The intervention group also received TCM intervention in addition to standard health care. The study was conducted over a three-year follow-up. At the end of three years follow-up, accumulative incidence and average annual incidence rate of diabetes in the control group was 43.86% and 14.62% respectively. Accumulative incidence and average annual incidence rate of diabetes in the TCM intervention group was 22.17% and 7.39% respectively. Compared with the control treatment, TCM intervention can reduce the relative risk of IGT patients progressing to type 2 diabetes by 49.45% and absolute risk by 21.69%. In the TCM intervention group, oral glucose tolerance test (OGTT), 2 h glucose, glycated hemoglobin, insulin resistance and body mass index were all significantly improved when compared to the control group. No significant side effect was observed during the follow-up in the TCM group. The SHCA-supported TCM intervention can reduce the conversion rate of IGT to diabetes and improve insulin resistance; therefore, it is a safe and effective IGT intervention strategy.