This study observed the efficacy and safety of JinqiJiangtang tablets (JQJT tablets, a traditional Chinese patent medicine) for pre-diabetes. Four hundred patients with pre-diabetes at five centres were treated for 12months and followed for an additional 12months to investigate the preventative effects of JQJT tablets (Registration ID: ChiCTR-PRC-09000401). The incidence rate of diabetes mellitus was the primary endpoint. The risk of converting from pre-diabetes to diabetes was 0.58-fold less in the JQJT tablets group than in the placebo group [HR (95% CI): 0.58 (0.384, 0.876), P = 0.010]. Furthermore, the probability of achieving normalized blood glucose was 1.41-fold greater in the JQJT tablets group than in the placebo group [HR (95% CI): 1.41 (1.002, 1.996), P = 0.0049]. ITT analysis revealed that the incidence of diabetes upon treatment completion was 16.5% in the JQJT tablets group compared with 28.9% in the control group. The percentage of patients with normalized blood glucose upon 12-month intervention was 41.8% in the JQJT tablets group compared with 27.8% in the control group. JQJT tablets could be an effective intervention for preventative treatment of Type 2 diabetes mellitus.