A systematic review and meta-analysis of α-lipoic acid in the treatment of diabetic peripheral neuropathy

Objective: To evaluate the effects and safety of 300-600 mg alpha-lipoic acid (ALA) given i.v. for diabetic peripheral neuropathy (DPN). Methods: We searched the databases of Medline, Embase, and Cochrane central register of Controlled Trials and Chinese biological medicine for clinical trials of ALA in the treatment of DPN. Data were extracted to examine methodological quality and describe characteristics of studies. The primary outcomes were efficacy, median motor nerve conduction velocity (MNCV), median sensory nerve conduction velocity (SNCV), peroneal MNCV, and peroneal SNCV. Secondary outcomes were adverse events. Results: Fifteen randomized controlled trials met the inclusion criteria. The treatment group involved the administration of ALA 300-600 mg i.v. per day. And the control group used the same interventions except for ALA. Compared with the control group, nerve conduction velocities increased significantly in the treatment group. The weighted mean differences in nerve conduction velocities were 4.63 (95% confidence interval 3.58-5.67) for median MNCV, 3.17 (1.75-4.59) for median SNCV, 4.25 (2.78-5.72) for peroneal MNCV, and 3.65 (1.50-5.80) for peroneal SNCV in favor of the treatment group. The odds ratio in terms of efficacy was 4.03 (2.73-5.94) for ALA. Furthermore, no serious adverse events were observed during the treatment period. Conclusions: The results of this meta-analysis provide evidence that treatment with ALA (300-600 mg/day i.v. for 2-4 weeks) is safe and that the treatment can significantly improve both nerve conduction velocity and positive neuropathic symptoms. However, the evidence may not be strong because most of the studies included in this meta-analysis have poor methodological quality.