During past several years, a novel class of antihyperglycemic agents, dipeptidyl peptidase-4 (DPP-4) inhibitors, has become one of the most important options in the management of type 2 diabetes. These agents have unique insulinotropic actions as well as other advantages such as lower hypoglycemia and a weight-neutral effect compared to traditional insulin secretagogues. To date, 6 different DPP-4 inhibitors have been introduced: sitagliptin, vildagliptin, saxagliptin, linagliptin, alogliptin and gemiglitin. This review provides a summary of the clinical data for each DPP-4 inhibitor, and discusses the similarities and differences between them