Chinese herbal medicine for diabetic peripheral neuropathy: an updated meta-analysis of 10 high-quality randomized controlled studies.

Background: Diabetic peripheral neuropathy (DPN) is very common in people with diabetes. Chinese herbal medicine (CHM) therapy has been developed for DPN empirically over the years. The aim of this systematic review and meta-analysis was to assess the efficacy and safety of CHMs for patients suffering from DPN.

Methods: We performed a meta-analysis of randomized-controlled clinical trials (RCTs) evaluating the efficacy and safety of CHM on DPN. Six databases were searched up to November 2012. The primary outcome measures were the absolute values or changing of motor or sensory nerve conduction velocity (NCV), and the secondary outcome measurements were clinical symptoms improvements and adverse events. The methodological quality was assessed by Jadad scale and the twelve criteria recommended by the Cochrane Back Review Group.

Results: One hundred and sixty-three studies claimed RCTs. Ten studies with 653 individuals were further identified based on the Jadad score ≥ 3. These 10 studies were all of high methodological quality with a low risk of bias. Meta-analysis showed the effects of NCV favoring CHMs when compared with western conventional medicines (WCM) (P<0.05 or P<0.01). There is a significant difference in the total efficacy rate between the two groups (P<0.001). Adverse effects were reported in all of the ten included studies, and well tolerated in all patients with DPN.

Conclusion: Despite of the apparently positive findings and low risk of bias, it is premature to conclude the efficacy of CHMs for the treatment of DPN because of the high clinical heterogeneity and small sample sizes of the included studies. However, CHM therapy was safe for DPN. Further standardized preparation, large sample-size and rigorously designed RCTs are required.