Safety of Metformin in Hospitalized Patients with COVID-19

Abstract

Background: It is unclear whether metformin should be continued or discontinued in patients with coronavirus disease 2019 (COVID-19) admitted to the hospital. Objective: To review metformin safety, particularly its impact on mortality among hospitalized patients with COVID-19. Methods: Review of English literature by PUBMED search until September 11, 2020. Search terms included diabetes, COVID-19, metformin, Retrospective studies, meta-analyses, pertinent reviews, pre-print articles, and consensus guidelines are reviewed. Results: Retrospective studies suggest that metformin use prior to hospital admission may be associated with decreased mortality in patients with diabetes admitted to the hospital with COVID-19. Continuing metformin use after hospital admission did not have a significant impact on 28-day all-cause mortality. Metformin use after hospitalization of patients with COVID-19 was associated with approximately 4.6 times increase risk of lactic acidosis in patients with severe symptoms of COVID-19, patients taking 2 gm/d of metformin or higher, and patients with estimated glomerular filtration rate (eGFR) less than 60 ml/min/1.73 kg/m2. Metformin use in the hospital was associated with a significant decrease in the risk of heart failure and acute respiratory distress syndrome (ARDS). Conclusions: In patients with diabetes and COVID-19 admitted to the hospital, metformin should not be used in presence of severe symptoms of COVID-19, kidney dysfunction (eGFR < 60 ml/min/1.73 m2), and with daily doses of 2 gm or more due to increased risk of lactic acidosis.