The miR-146a deficiency observed in diabetes leads to enhanced inflammation and increased synthesis of MCP-1, followed by further reduction in miR-146a by enhancing the signaling of systemic effects by TGF-β1/Erb-B2 receptor tyrosine kinase 4 (ErbB4)/neurogenic locus notch homolog protein 1 (Notch1) accompanying severe COVID-19; this may explain the more severe COVID-19 cases occurring in these patients [141]. This evidence concerns the gene ERBB4 and diabetes mellitus.