Should metformin be continued after hospital admission in patients with COVID-19?

Nasser Mikhail, Soma Wali


In most patients with diabetes, guidelines recommend discontinuation of oral anti-diabetic agents. Preliminary data suggest that pre-admission metformin use may have mortality benefit in patients with coronavirus disease 2019 (COVID-19) admitted to the hospital. To review metformin safety, particularly its impact on mortality among hospitalized patients with COVID-19. Review of English literature by PubMed search until September 18, 2020. Search terms included diabetes, COVID-19, metformin, retrospective studies, meta-analyses, pertinent reviews, pre-print articles and consensus guidelines are reviewed. Retrospective studies suggest that metformin use prior to hospital admission may be associated with reduction in mortality among patients with diabetes admitted to the hospital with COVID-19. Meanwhile, continuing metformin administration after hospital admission did not have 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 intake in hospital was associated with significant decrease risk of heart failure and acute respiratory distress syndrome (ARDS). 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.


COVID-19, Diabetes, Metformin, Safety, Mortality, Lactic acidosis


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