Twelve months’ oral supplementation of vitamin B12 (Methylcobalamin) 1 mg is beneficial in increasing plasma B12 levels and improving all neurophysiological factors, sudomotor function, pain score, and quality of life of diabetic neuropathic patients (both peripheral and autonomic).

This prospective, double-blind, placebo-controlled trial of 90 patients with type-2 diabetes on metformin therapy for a minimum of 4 years examined the effect of regularizing vitamin B12 levels with vitamin B12 taken orally for a year. The active treatment group had 44 patients receiving B12 and control group had 46 patients receiving a placebo. These patients had >400 pmol/L B12 levels. The electrodiagnostic evaluation and cardiovascular autonomic reflex tests (CARTs) were performed. SUDOSCAN was used to calculate electrochemical skin conductance in hands and feet i.e. ESCH and ESCF. Quality of life and pain intensity was evaluated via the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE).

In the active group, vitamin B12 levels augmented from 232.0 ± 71.8 from initiation to 776.7 ± 242.3 pmol/L at follow-up, however not in the placebo group. Also, significant improvements were observed in the pain score, improved quality of life, VPT (vibration perception threshold), MNSIQ, sural nerve conduction velocity (SNCV), sural nerve action potential (SNAP), and ESCF in the active group but not in the control group. The CARTs and MNSIE did not improve significantly. No clinically significant adverse events were reported during the study.