Metformin use is associated with a reduced risk of mortality in patients with diabetes hospitalized for COVID-19

ABSTRACT

Metformin exerts anti-inflammatory and immunosuppressive effects. We addressed the impact of prior metformin use on the prognosis of patients with type 2 diabetes hospitalised for COVID-19. We used data from the nationwide observational CORONADO cohort that included patients with diabetes hospitalised for COVID-19 between March 10 and April 10, 2020 in 68 French centres. The primary outcome was combined tracheal intubation and/or death within 7 days of admission. A Kaplan–Meier survival curve was reported for death up to day 28. The association between metformin use and outcomes was then estimated in a logistic regression analysis after applying propensity score weighting approach to account for treatment allocation. Among the 2449 patients included, 1496 were metformin users and 953 were not. Compared with non-users, metformin users were younger with a lower prevalence of diabetic complications, but had more severe features of COVID-19 at admission. The most striking feature was a lower mortality rate in metformin users vs. non-users on day 7 (8.2 % vs. 16.1 %, respectively;P < 0.0001) and on day 28 (16.0 % vs. 28.6 %, respectively P < 0.0001), even after propensity score weighting was applied. Randomised, controlled studies are now needed in order to confirm the benefits associated with metformin and to establish to what extent these protective effects, if any, can be generalised to non-diabetic patients with COVID-19.