A prospective, open label, 24-week trial of methylcobalamin in the treatment of diabetic polyneuropathy

Abstract

Introduction: Vitamin B complex has been used for peripheral neuropathy for a long time and continues to be part of current practice despite lack of strong evidence for its use and its non-inclusion in treatment guidelines. Objective: To determine the clinical and neurophysiological effects of 1500 μgm/day of oral methylcobalamin among subjects with diabetic polyneuropathy. Methodology: We conducted a prospective, open-label study on adult diabetic subjects with polyneuropathy who were given 1500 μgm/day of oral methylcobalamin over 24-weeks. The primary outcome measure was the Toronto Clinical Scoring System (CSS) and secondary measures were Subjective Impression of Change, Clinicians Impression of Change and neurophysiological parameters. Results: Out of forty eight subjects, thirty seven completed treatment and twenty one agreed to have repeat neurophysiologic study post-treatment. At the end of treatment, there was a significant decline in the Toronto CSS score (p < 0.0001) indicating improvement. This was observed across all stages of severity and in any duration of diabetes whether more or less than 10 years. The symptoms that improved compared to baseline and that did not emerge over the course of 24 weeks were tingling (p < 0.03), upper limb symptoms (p < 0.003), ataxia (p < 0.004), and signs of impaired position (P < 0.009) sense, vibration sense (p < 0.0001), pinprick sensation (p < 0.004) and knee reflex (p < 0.004). No significant improvement was seen in the secondary outcomes (both p=0.06) except for ulnar nerve amplitude and distal latency. Conclusion: This 24-week open label study demonstrated that symptoms of diabetic polyneuropathy significantly improved among subjects given methylcobalamin 1500 μgm/day and new symptoms did not emerge over the 24 week observation period. Larger controlled trials are needed to corroborate these findings.