DPP4 and type 2 diabetes mellitus: To explore the level of sCD26, serum samples from young and old controls [age-matched T2DM: n=50, 30–55 years; non-demented) and ARD (n=50, aged between 56 and 85 years) subjects were analysed by sandwich enzyme-linked immunosorbent assay (ELISA) using Human DPP4/CD26 (R&D system, catalogue number: DY1180).