A potent DPP-4 inhibitor (Ki = 0.6 nM); inhibits DPP-4 ex vivo (ED50 = 0.12 μmol/kg) in plasma from normal fasted rats; reduces plasma glucose levels in Zuckerfa/fa diabetic rats in a dose-dependent manner when administered orally in doses ranging from 0.3-3 mg/kg; increases plasma insulin levels and improves glucose clearance in ob/ob mice; induces systolic and diastolic dysfunction, reduces contractile force, and exacerbates ischemia-reperfusion injury-induced cardiac dysfunction in isolated guinea pig hearts