GLP1R and diabetes mellitus: Diabetes is usually treated and controlled by prescribing synthetic antidiabetic drugs such as biguanides (metformin), sulphonylureas (glibenclamide), thiazolidinediones (pioglitazone), alpha-glucosidase inhibitors (acarbose), DPP-4 inhibitors (sitagliptin), glinides (repaglinide) and GLP-1 agonists (exenatide) [7].