Abstract
Metformin-associated lactic acidosis (MALA) is an extremely rare but life-threatening adverse effect of metformin treatment. The lifestyle changes associated with the coronavirus disease 2019 (COVID-19) pandemic may increase the potential risk of MALA development in patients with diabetes. We herein report a 64-year-old Japanese man taking a small dose of metformin who presented with MALA accompanied by hypoglycemia secondary to increased alcohol consumption triggered by lifestyle changes during the pandemic. Physicians should prescribe metformin judiciously to prevent MALA development and pay close attention to lifestyle changes in patients at risk for MALA during the COVID-19 pandemic.