BACKGROUNDComorbidities such as obesity and type 2 diabetes mellitus (T2DM) have emerged as critical risk factors exacerbating the severity and mortality of COVID-19. Meanwhile, numerous genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with increased susceptibility to severe COVID-19.AIMThis study investigated whether SNPs previously identified by GWAS as risk factors for severe COVID-19 also correlate with common comorbidities-obesity and T2DM-in hospitalized patients with severe COVID-19.METHODSDNA samples from 199 hospitalized COVID-19 patients were genotyped using probe-based PCR for 10 GWAS SNPs previously implicated in severe COVID-19 outcomes (rs143334143 CCHCR1, rs111837807 CCHCR1, rs17078346 SLC6A20-LZTFL1, rs17713054 SLC6A20-LZTFL1, rs7949972 ELF5, rs61882275 ELF5, rs12585036 ATP11A, rs67579710 THBS3, THBS3-AS1, rs12610495 DPP9, rs9636867 IFNAR2).RESULTSThe analysis revealed significant associations between certain SNPs and the increased risk of obesity and T2DM in severe COVID-19 patients. Specifically, rs17713054 SLC6A20-LZTFL1 (risk allele A; odds ratio (OR) = 2.34, 95% confidence interval (CI) = 1.24-4.4, p = 0.007) and rs7949972 ELF5 SNP (risk allele T; OR = 1.79, 95% CI = 1.11-2.91, p = 0.015) were associated with increased risk of obesity. SNP rs9636867 IFNAR2 was associated with a higher risk of T2DM (risk allele G, OR = 8.28, 95% CI = 1.69-40.64, p = 0.027). Using the model-based multifactor dimensionality reduction (MB-MDR) approach, the six most significant gene-gene interaction patterns associated with obesity in severe COVID-19 patients were identified and included five polymorphic loci: rs7949972, rs17713054, rs61882275, rs12585036, and rs143334143, participating in two or more of the most significant G-G interactions (pperm < 0.05). In total, the best models of G-G interactions associated with T2DM in patients with severe COVID-19 included eight polymorphic loci, six of which, rs7949972, rs61882275, rs12585036, rs143334143, rs67579710, and rs12610495, were involved in two or more of the most significant G-G interactions.CONCLUSIONSOur study provides novel insights into the genetic associations between GWAS-identified SNPs and the risk of obesity and T2DM in patients with severe COVID-19.