Effects Of Methylcobalamin On Diabetic Peripheral Neuropathy: A Systematic Review Of Randomized Evidence

Background Peripheral neuropathy is one of the most common diabetic chronic complications. So far, there are no definitively effective treatments for diabetic peripheral neuropathy and intensive control of blood glucose has been regarded as the fundamental treatment. However, the nerve function has not been completely improved in some patients who have suffered from this disease for a certain time. Moreover, there is more chance to suffer from serious hypoglycemia. So other treatments must be administered based on the intensive control of blood glucose. Recently there have been many small-sample randomized clinical trials about the effects of methylcobalamin on diabetic peripheral neuropathy. Methylcobalamin has been verified effectively in the relief of the clinical symptoms and signs of diabetic peripheral neuropathy, the increase of the nerve conduction velocity and the improvement of the quality of life of the patients.Objective To review systematically whether there is enough existing evidence that methylcobalamin is effective and safe in the treatment of thepatients with diabetic peripheral neuropathy.Method A Cochrane systematic review of all relevant randomized or quasi-randomized controlled trials of methycobalamin for diabetic peripheral neuropathy was performed. Clinical trials were searched from Cochrane Controlled Trials Register, Medline, Embase, The Chinese Biological Medicine Database, The Chinese Science and Technology Journal Full-text Database and references of all included trials. The selection of studies, data extraction and assessment of methodological quality were performed independently by two reviewers. The following outcomes were assessed: effectivenss of clinical symptoms and signs, sensory nerve and motor nerve conduction velocities and serious adverse events of methylcobalamin. Results Forty-three randomized clinical trials including 2782 patients met the inclusion criteria. The quality of the most included trials was of low level. "Funnel plot" of comparison of effects of methylcobalamin with that of routine treatment showed asymmetry, which indicated possible publication bias and was related to low quality in methodology and small sample. "Funnel plot" of comparison of effects of methylcobalamin with that of other Vitamin B showed symmetry, which indicated less possible publication bias and the result was partly reliable. The results of Meta-analysis indicated that methylcobalamin showed significantly positive effects on the improvement of the symptoms and signs of peripheral neuropathy, and the effects are better than the other vitamin B. The increase of some nerves conduction velocities by methylcobalamin was better than by the other vitamin B. The improvement of the symptoms and signs and some nerves conduction velocities of peripheral neuropathy by Chinese medical herbs were betterthan by methylcobalamin. The effects of methylcobalamin were similar to medicines of improving microcirculation such as prostaglandin E. No serious adverse events were observed during the treatment period. Conclusions Methylcobalamin appears to be a safe and effective treatment on diabetic peripheral neuropathy. However, the evidence is not enough strong because of the low qualities of trials and publications bias. Rigorously designs, randomized, double-blind, placebo-controlled trials of methylcobalamin for diabetic peripheral neuropathy are needed to further assess the effect.