Notably, when adjusting for age, male gender, BMI, DM, and serum markers of COVID-19 severity such as CRP, D-dimer, and ferritin, IL-17 saliva level remained significantly associated with disease severity (Fig 1C and 1D, adjusted P<0.001; and AUC of 0.94 [95% CI, 0.90–0.98]). This evidence concerns the gene IL17A and diabetes mellitus.