Orally active, potent and selective dipeptidyl peptidase IV (DPP-IV; DPP4) inhibitor that improves glucose tolerance in vivo.

Sitagliptin is an orally active, potent and selective dipeptidyl peptidase IV (DPP4; DPP-IV) inhibitor (IC50 = 18 nM) with excellent selectivity over other proline-selective peptidases (IC50 = 48 μM/DPP8, >100 μM/DPP9 & QPP). Sitagliptin improves glucose tolerance in lean mice (23% and 55% reduction of blood glucose post 5 g dextrose/kg with 0.1 or 3 mg Sitagliptin/kg p.o. 60 min prior to dextrose challenge) and in DIO mice (68% and 90% reduction of blood glucose post 2 g dextrose/kg with 0.3 or 3 mg Sitagliptin/kg p.o.) as a result of DPP-IV inhibition and upregulated GLP-1 level in blood in vivo.