Red ginseng for type 2 diabetes mellitus: A systematic review of randomized controlled trials

Objective: Red ginseng (RG, Panax ginseng C.A. Meyer) is one of the widely used herbs for treating type 2 diabetes mellitus (DM). However, no systematic review of the effectiveness of RG for type 2 DM is available. This systematic review aimed to evaluate the current evidence for the effectiveness of RG in patients with type 2 DM. Methods: Electronic searches of 14 electronic databases were conducted without language restrictions. All randomized clinical trials (RCTs) with RG as a treatment for type 2 DM were considered for inclusion. Their methodological quality was assessed using the Cochrane criteria. Results: Four RCTs met our inclusion criteria. Their methodological quality was variable. Three of the RCTs compared the effectiveness of RG with placebo. The meta-analysis of these data failed to favor RG over placebo for fasting plasma glucose (FPG) [n=76, weighted mean difference (WMD): -0.43 mmol/L; 95% confidence interval (CI): -1.16 to 0.30, P=0.25] and fasting plasma insulin (FPI) (n=76, WMD: -8.43 pmol/L; 95% CI: -19.54 to 2.68, P=0.14) for 12 weeks of treatment. One RCT compared the effects of RG with no treatment. The results did not suggest favorable effects of RG on FPG, hemoglobin A_1c (HbA _1c) or 2-h blood glucose after a meal (PP2h). Conclusions: The evidence for the effectiveness of RG in controlling glucose in type 2 DM is not convincing. Few included studies with various treatment regimens prohibit definitive conclusions. More rigorous studies are needed to clarify the effects of RG on this condition.