Is vitamin B₁₂ supplementation important in diabetic neuropathy? Original paper

Vitamin B12 deficiency is common in type 2 diabetes, and because of its importance in maintaining the health of the nervous system, this deficiency has been hypothesized to contribute to diabetic neuropathy.

In this 12-month randomized double-blind placebo-controlled trial, 90 participants with type 2 diabetes who were taking metformin also took 1 mg of methylcobalamin B₁₂ or a placebo daily.

The researchers applied a number of tests, including the Michigan Neuropathy Screening Instrument Questionnaire (MNSIE) and the Michigan Neuropathy Screening Instrument Examination (MNSIE) (both of which evaluate neuropathy symptoms), the Diabetes Quality of Life questionnaire (evaluates general health and functioning issues in diabetes), sural nerve action potential and velocity (SNCV; evaluates the activity of a nerve in the foot), vibration perception threshold (VPT; tests the sensitivity of nerves to a pain stimulus), cardiovascular autonomic reflex tests (CARTs), pain score, and electrochemical skin conductance in feet and hands (ESCF and ESCH; tests of sudomotor function)

The vitamin B12 group saw improvements in MNSIQ, quality of life, pain score, SNCV, and ESCF compared to the placebo group. Evaluations of CARTs, ESCH, and MNSIE did not show improvements. Glycated hemoglobin was also evaluated, with no differences detected, and the vitamin B12 group saw an increase from 232 ± 71.8 to 776.7 ± 242.3 pmol/L compared with only a small increase for placebo.

There were no adverse events and no meaningful differences on a variety of standard biochemical blood tests.