Background and Aim Currently, the number of patients with coronavirus disease 2019 (COVID-19) infection is increasing rapidly worldwide. In this study, we aimed to assess whether diabetes mellitus (DM) would increase the risk of severe infection and death in patients with COVID-19. Methods We systematically searched the PubMed, Web of Science, MedRxiv and COVID-19 academic research communication platform for studies reporting clinical severity and/or overall mortality data on DM in patients with COVID-19 published up to July 10, 2020. The primary outcome was to compare the severe infection rate and mortality rate in COVID-19 patients with and without DM, and to calculate the odds ratio (OR) and 95% confidence interval (CI). Results A total of 77 studies involving 32,015 patients with COVID-19 were included in our meta-analysis. COVID-19 patients with DM had higher severe infection and case-mortality rates compared with those without DM (21.4 vs. 10.5% and 28.3 vs. 13.1%, respectively, all p <0.01). COVID-19 patients with DM were at significantly elevated risk of severe infection (OR = 2.49, 95% CI: 2.10-2.95, p <0.001) and mortality (OR = 2.22, 95% CI: 1.80-2.47, p <0.001). Conclusion
Adults (18+) Elderly (65+) Risk group Risk factor COVID-19