DPP-4 inhibitors (DPP-4i, also known as gliptins) have been widely used since 2006 as oral antihyperglycemic agents for the treatment of T2D and have been proven effective in improving glucose control by preventing the DPP-4-mediated cleavage and inactivation of incretin hormones, enhancing endogenous insulin secretion and suppressing glucagon secretion [14]. This evidence concerns the gene GCG and type 2 diabetes mellitus.