Prevention of Type 2 Diabetes with the Chinese Herbal Medicine Tianqi Capsule: A Systematic Review and Meta-Analysis

Introduction: Prevention of the rapid growth in incidence of type 2 diabetes (T2DM) is a big challenge for clinicians. In China, many trials have indicated that Tianqi capsule, which contains several Chinese herbal medicines as part of a large healing system called traditional Chinese medicine, could decrease the incidence of T2DM. The review assessed the effectiveness of Tianqi capsule in prevention of T2DM. Methods: Seven electronic databases were searched to identify eligible trials published from the inception of the databases up until May 1, 2017. Randomized controlled trials (RCTs) of Tianqi capsule for impaired glucose tolerance (IGT) were included. Data extraction and quality assessment were performed according to the Cochrane review standards. A random or a fixed effect model was used to analyze outcomes which were expressed as risk ratios (RRs) or mean differences (MD), and I 2 statistics were used to assess heterogeneity. Results: Six trials were identified that included 1027 subjects. Meta-analysis showed that subjects who received Tianqi capsule plus lifestyle modification (LM) were less likely to progress to T2DM compared to controls (RR 0.55, 95% CI 0.44-0.68). Subjects who received Tianqi capsule plus LM were more likely to have glucose return to normal compared to controls (RR 0.69; 95% CI 0.62-0.78); and they had reduced fasting plasma glucose (FBG) (MD -0.35; 95% CI -0.55 to -0.16) and 2-h plasma glucose (2 h PG) (MD -1.04; 95% CI -1.75 to -0.32). There was no statistical difference between the two groups for IGT stabilized incidence (RR 0.89; 95% CI 0.71-1.12). No obvious adverse events occurred. Conclusion: In patients with IGT, Tianqi capsule reduced the risk of progression to T2DM and increased the possibility of regression toward normoglycemia. As a result of the limited number of RCTs and the methodological drawbacks of the included studies, the results should be interpreted with caution.