Research progress on serum vitamin B12 reduction induced by metformin

Metformin is a drug which has been widely used in clinical practice. Multiple clinical trials have suggested that long-term use of metformin could result in serum vitamin B12 reduction even deficiency, while vitamin B12 deficiency might lead to peripheral neuropathy, megaloblastic anemia and aggravation of preexisting cardiovascular diseases in diabetic patients. Vitamin B12 deficiency-induced neuropathy is easily misdiagnosed as diabetic neuropathy. However, the incidence of vitamin B12 reduction induced by metformin intervention varies among different studies, and the underlying mechanisms are not fully elucidated. In this paper, research progress on vitamin B12 reduction caused by metformin was reviewed and the possible reasons of differences in the incidence rate were analyzed, aiming to identify, prevent and treat vitamin B12 reduction caused by metformin.