Gutniak et al. [68,69] and Nathan et al. [68,69] evaluated the effects of GLP-1 in both type 2 diabetes patients and healthy nondiabetic controls, and a number of GLP-1R agonists (i.e., the short-acting exendin-4-based agonists exenatide and lixisenatide and the long-acting agonists albiglutide, dulaglutide, exenatide-LAR, and liraglutide) and DPP-4 inhibitors (i.e., sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin) have been used for the treatment of poor glycemic control in patients with type 2 diabetes [63,70]. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.