A DPP-4 inhibitor (IC50 = 18 nM); selective for DPP-4 over DPP-8 (IC50 = 48 μM) as well as several other peptidases; improves glucose tolerance in insulin-resistant Zucker fatty and high-fat diet fed rats as well as and high-fat diet fed mice; reduces hyperglycemia in mice fed a high-fat diet with streptozotocin-induced diabetes,