Firstly, fifteen hub targets of 1,25(OH)2D against COVID-19/DM included EGFR, PIK3R1, PIK3CA, STAT3, MAPK1, ESR1, HSP90AA1, LCK, MTOR, IGF1, AR, NFKB1, PIK3CB, PTPN1, and MAPK14 were identified by applying network pharmacology that is a frequently-used approach to pharmaceutical research for multiple diseases included COVID-19 and DM. The gene discussed is ESR1; the disease is diabetes mellitus.