INS and COVID-19: Additional comparison of COVID-19 patients with different insulin sensitivity and the control group demonstrated that COVID-19 patients with HOMA-IR ≤3 and >3 had significantly lower fetuin-A levels than the control group (256.7 (230.6–314.0) vs. 333.5 (303.0–371.4) μg/mL; p = 0.001 and 231.2 (190.7–276.1) vs. 333.5 (303.0–371.4) μg/mL; p < 0.001, respectively).