A DPP-4 inhibitor (IC50 = 10.8 nM), selective for DPP-4 over DPP-8 and DPP-9 (IC50s = >100 µM for both) and a panel of 127 receptors, ion channels, transporters, and enzymes at 10 µM, decreases blood glucose levels, increases serum insulin levels, and inhibits serum DPP-4 activity in an oral glucose tolerance test...