The Independent Risk of Obesity and Diabetes and Their Interaction in COVID-19: A Retrospective Cohort Study.

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.