According to the current guidelines, the first-line therapy for T2DM uses metformin, followed by either sodium-glucose cotransporter 2 inhibitor (SGLT2i), dipeptidyl peptidase-4 inhibitor (DPP4i), α-glucosidase inhibitor, or sulfonylureas (Qaseem et al., 2017; Flory and Lipska, 2019; Grant and Cosentino, 2019; Dong et al., 2023). The gene discussed is DPP4; the disease is type 2 diabetes mellitus.