A Case of Metformin-Related Megaloblastic Anemia Presenting with Palpitation

Metformin is the cornerstone of medical treatment in most diabetic patients with many beneficial effects on cardio-metabolic parameters. However, long term metformin is a known pharmacological cause of vitamin B12 deficiency leading to neurological symptoms, megaloblastic anemia and increased levels of serum homocysteine. Moreover, it is well known that vitamin B12 deficiency-induced neurologic symptoms precede the appearance of megaloblastic anemia. Case:We herein report the case of an old woman with a history of long term metformin consumption who visited the cardiology clinic with the chief complaint of palpitation due to megaloblastic anemia without any neuropsychiatric symptoms. She was successfully treated with a parenteral regimen of vitamin B12 within two months. Although annual measurement of serum vitamin B12 levels could be considered in patients on long-term metformin therapy, yet it seems more reasonable and cost-effective to prevent vitamin B12 deficiency and its related adverse effects with annual prescription of parenteral vitamin B12 in all such patients.