The intersection between periodontitis, T2DM and COVID-19 disease (Sukumar and Tadepalli, 2021; Brock et al., 2022), occurs when during diabetes mellitus, there is an increase in blood glucose levels (hyperglycemia) and together with the viral infection, an exacerbated inflammatory response is triggered, increasing the production of TNF-α. The gene discussed is TNF; the disease is diabetes mellitus.