GLP1R and type 2 diabetes mellitus: Two different therapeutic options have been identified to compensate for the low incretin effect in T2DM patients, either by inhibiting dipeptidyl dipeptidase-4 (DPP-4), an enzyme that rapidly inactivates GIP and GLP-1 (sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin) or by inhibiting the mimetic drug GLP-1 (liraglutide, exenatide, dulaglutide, albiglutide, lixisenatide).