Synthetic GLP-1R agonists (GLP-1RA) which are resistant to degradation by DPP-4, and DPP-4 inhibitors which prevent GLP-1 degradation, thereby increasing the plasma levels of endogenous GLP-1, are now in widespread clinical use for T2DM [42,43]. This evidence concerns the gene DPP4 and type 2 diabetes mellitus.