Notably, DPP4, also known as CD26, contributes to glucose homeostasis by inactivating glucagon-like peptide-1 (GLP-1), an incretin hormone that downregulates glycaemia, and DPP4 inhibitors have been a therapy for managing type 2 diabetes mellitus (T2DM) since 2006 [2–6]. The gene discussed is GCG; the disease is type 2 diabetes mellitus.