Association between metformin use and vitamin B12 deficiency in patients with type 2 diabetes

Abstract

Metformin is one of the most widely used oral anti-hyperglycemic agents. Adverse effect of metformin is disturbance in vitamin B12 metabolism associated with low serum vitamin B12 level. Vitamin B12 hypovitaminosis is accompanied by peripheral neuropathy. The long-term use can cause anemia and increase the risk of depression, cerebrovascular and neurodegenerative diseases. Clinical studies and meta-analyses have constantly confirmed the association between metformin use and vitamin B12 hypovitaminosis. It was shown that every 25 pmol/l increase in B12 level was associated with a 6% reduction in the risk of neuropathy. The application of B12 would help compensate the disturbances in vitamin B12 metabolism caused by metformin.