DPP4 and type 2 diabetes mellitus: In the last decade, three new classes of anti-hyperglycemic drugs with putative glucose-independent effects have been successfully introduced for the management of T2DM: glucagon-like peptide-1 receptor (GLP-1R) agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, and sodium–glucose cotransporter 2 (SGLT2) inhibitors [9].