DPP4 and infection: Using existing DPP4 inhibitors (such as sitagliptin, linenegliptin, vildagliptin, etc.)to inhibit the activity of DPP4/CD26 may be an effective weapon to block the host CD26 receptor, thereby blocking SARS CoV- 2 Enter T cells to prevent infection of COVID-19.[9] Furthermore, as a class of oral hypoglycemic agents, DPP-4 inhibitors can effectively reduce glycosylated hemoglobin.