Three ubiquitous serum proteins that are involved in cell repair and immunity, alpha-2 macroglobulin (A2M) [9,10,11,12], apolipoprotein A1 (ApoA1) [9,10,13,14], and haptoglobin [9,10,15,16,17,18], which are mainly synthetized by the liver, are associated with the risk of being infected with COVID-19 and are associated with the severity of its complications compared with controls without diabetes nor NAFLD [9,10,11,12,13,14,15,16,17,18]. The gene discussed is APOA1; the disease is diabetes mellitus.