These results led us to construct a PPI network and use two machine learning algorithms to identify diagnostic biomarkers that were present in T1DM and COVID-19 convalescence: CD3G, YES1, ALAS2, MYO1C, NCR3, and PRKACB. Among these genes, CD3G and YES1 interacted with most of the other genes. The gene discussed is CD3G; the disease is COVID-19.