Delayed auditory conduction in diabetes: is metformin-induced vitamin B12 deficiency responsible?

Abstract

SummaryThe present study aims to evaluate the functional integrity of the auditory pathway in patients with diabetes taking metformin. A further aim is to assess its association with vitamin B12 deficiency induced by metformin. Thirty diabetics taking metformin and 30 age-matched non-diabetic controls were enrolled. Stimulus-related potentials and vitamin B12 levels were evaluated in all the subjects. The diabetics showed deficient vitamin B12 levels and delayed wave III latency and III-V interpeak latency in the right ear and delayed Na and Pa wave latencies in the left ear compared with the controls. The dose and duration of metformin showed no association with the stimulusrelated potentials. Therefore, although vitamin B12 levels were deficient and auditory conduction impairment was present in the diabetics on metformin, this impairment cannot be attributed to the vitamin B12 deficiency.

The relationship between exacerbated diabetic peripheral neuropathy and metformin treatment in type 2 diabetes mellitus

“…The aim of this study was to assess whether metformin is a risk factor for the development of DPN by evaluating the impact of metformin on the serum level of cobalamin and homocysteine in type 2 DM. Most of the past clinical studies demonstrated that metformin has some impact on plasma cobalamin and homocysteine and there are some case reports indicating deterioration of neuropathy with metformin 29 – 32 . Some recent researches have investigated the relation of metformin with the level of cobalamin and neuropathy with conflicting results 29 , 33 , 34 .…”