Highlights There are ~ 2-fold increased odds of severe coronavirus disease 2019 (COVID-19) and a ~ 2-fold increased risk of odds of mortality in patients with history of diabetes mellitus compared to those without diabetes mellitus. Patients with a history of diabetes mellitus should be closely monitored if they get infected with COVID-19. Results of meta-analysis showing association of diabetes mellitus with severity (Panel A) of disease and mortality (Panel B) in coronavirus disease 2019 (COVID-19) patients.