Mendelian randomization study of obesity and type 2 diabetes in hospitalized COVID-19 patients

Background: Both obesity and type 2 diabetes (T2D) are reported to be highly enriched in hospitalized COVID-19 patients. Due to the close correlation between obesity and T2D, it is important to examine whether obesity and T2D are independently related to COVID-19 hospitalization. Objective: To examine the causal effect of obesity and T2D in hospitalized COVID-19 patients using Mendelian randomization (MR). Research design and methods: This two-sample MR analysis applied genetic markers of obesity identified in the genome wide association study (GWAS) by the GIANT Consortium as instrumental variables (Ws) of obesity; and genetic markers of T2D identi tied by the DIAGRAM Consortium as IVs of T2D. The MR analysis was performed in hospitalized COVID-19 patient by the COVID-19 Host Genetics Initiative using the MR-Base platform. Results: All 3 classes of obesity (Class 1/2/3) were shown as the causal risk factors of COVID-19 hospitalization; however, T2D doesn't increase the risk of hospitalization or critically ill COVID-19 as an independent factor. Conclusions: Obesity, but not T2D, is a primary risk factor of COVID-19 hospitalization. (C) 2022 Elsevier Inc. All rights reserved.