DPP4 and type 2 diabetes mellitus: Only metformin and thiazolidinediones have such an effect, while the main mechanism of action of other medications used for T2DM treatment is the increase of insulin secretion (Glucagon-like peptide-1 receptor agonists (GLP-1), Dipeptidyl peptidase-4 inhibitors (DPP-4), sulfonylurea derivatives), a decrease in glucose absorption in the gastrointestinal tract (acarbose) or increased glucose kidney excretion (sodium glucose co-transporter-2 (SGLT2) inhibitors) [5].