OBJECTIVE: This study aimed to assess whether diabetes mellitus (DM) or obesity is an independent risk factor for severe coronavirus disease 2019 (COVID-19) outcomes and to explore whether the risk conferred by one condition is modified by the other. METHODS: This retrospective cohort study of inpatient adults with COVID-19 used multivariable Cox regression to determine the independent effects of DM and obesity on the composite outcome of intubation, intensive care unit admission, or in-hospital mortality. Effect modification between DM and obesity was assessed with a statistical interaction term and an exploration of stratum-specific effects. RESULTS: Out of 3,533 patients, a total of 1,134 (32%) had DM, 1,256 (36%) had obesity, and 430 (12%) had both. DM and obesity were independently associated with the composite outcome (hazard ratio [HR] 1.14 [95% CI: 1.01-1.30] and HR 1.22 [95% CI: 1.05-1.43], respectively). A statistical trend for potential interaction between DM and obesity was observed (P = 0.20). Stratified analyses showed potential increased risk with obesity compared with normal weight among patients with DM (HR 1.34 [95% CI: 1.04-1.74]) and patients without DM (HR 1.18 [95% CI: 0.96-1.43]). CONCLUSIONS: DM and obesity are independent risk factors associated with COVID-19 severity. Stratified analyses suggest that obesity may confer greater risk to patients with DM compared with patients without DM, and this relationship requires further exploration.
The Independent Risk of Obesity and Diabetes and Their Interaction in COVID-19: A Retrospective Cohort Study