Letter to the Editor

More Adverse Neurological Consequences of Metformin-Induced Vitamin B12 Deficiency

Authors: Eileen Moore, BSc(Hons), Alastair Mander, BmedSci, MBBS, FRACP, David Watters, BSc, MB, ChB, FRCSEd, ChM, FRACS

Abstract

To the Editor: We read with interest the landmark first case report of metformin-induced vitamin B12 deficiency causing neuropathy in a 69-year-old man having used metformin for three years by Dr. David Bell.1The link between metformin and neuropathy is further supported by a prospective case-control study conducted in 122 diabetics; fifty-nine of which had been treated with metformin for more than six months.2 The metformin treated patients were found to have depressed serum vitamin B12 levels and more severe clinical and electrophysiological measures of peripheral neuropathy.

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References

1. Bell DSH. Metformin-induced vitamin B12 deficiency presenting as a peripheral neuropathy. South Med J 2010;103:265-267.
 
2. Wile DJ, Toth C. Association of metformin, elevated homocysteine, and methylmalonic acid levels and clinically worsened diabetic peripheral neuropathy. Diabetes Care 2010;33:156-161.
 
3. Herbert V. Staging vitamin B-12 (cobalamin) status in vegetarians. Am J Clin Nutr 1994;59(5 suppl):1213S-1222S.
 
4. Chen Y, Zhou K, Wang R, et al. Antidiabetic drug metformin (Glucophage) increases biogenesis of Alzheimer's amyloid peptides via up-regulating BACE1 transcription. Proc Natl Acad Sci U S A 2009;106:3907-3912.