ABSTRACT
AIMS/INTRODUCTION: Diabetes mellitus is reported as a risk factor for increased coronavirus disease 2019 (COVID-19) severity and mortality, but there have been few reports from Japan. Associations between diabetes mellitus and COVID-19 severity and mortality were investigated in a single Japanese hospital. MATERIALS AND METHODS: Patients aged ≥20 years admitted to Osaka City General Hospital for COVID-19 treatment between April 2020 and March 2021 were included in this retrospective, observational study. Multivariable logistic regression analysis was carried out to examine whether diabetes mellitus contributes to COVID-19-related death and severity. RESULTS: Of the 262 patients included, 108 (41.2%) required invasive ventilation, and 34 (13.0%) died in hospital. The diabetes group (n = 92) was significantly older, more obese, had longer hospital stays, more severe illness and higher mortality than the non-diabetes group (n = 170). On multivariable logistic regression analysis, age (odds ratio [OR] 1.054, 95% confidence interval [CI] 1.023-1.086), body mass index (OR 1.111, 95% CI 1.028-1.201), history of diabetes mellitus (OR 2.429, 95% CI 1.152-5.123), neutrophil count (OR 1.222, 95% CI 1.077-1.385), C-reactive protein (OR 1.096, 95% CI 1.030-1.166) and Krebs von den Lungen-6 (OR 1.002, 95% CI 1.000-1.003) were predictors for COVID-19 severity (R2 = 0.468). Meanwhile, age (OR 1.104, 95% CI 1.037-1.175) and Krebs von den Lungen-6 (OR 1.003, 95% CI 1.001-1.005) were predictors for COVID-19-related death (R2 = 0.475). CONCLUSIONS: Diabetes mellitus was a definite risk factor for COVID-19 severity in a single Japanese hospital treating moderately-to-severely ill patients.