The present invention is directed to compounds of formula (I): or a pharmaceutically acceptable salt thereof; wherein A is (II); X is selected from CH, CF and N, R8 is selected from H, C1-C6 alkyl, aryl, heteroaryl, C1-C6 alkylaryl, C1-C6 alkylheteroaryl, C2-C6 alkyl-O—C1-C6 alkyl, C1-C6 haloalkyl, hydroxy C2-C6 alkyl, —C(O)R9 and —SO2R9, or R7 and R8 combine to form (III), (IV); W is selected from CR1O and CR15, R1O is selected from H, halo, —C(O)NR13R14, C1-C6 alkyl, aryl, heteroaryl, C1-C6 alkylaryl, C1-C6 alkylheteroaryl, C1-C6 alkyl-O—C1-C6 alkyl and hydroxy C1-C6 alkyl; Het is a N-linked 5-membered heteroaryl ring optionally substituted with 1-3 substituents selected from methoxy, Cl, F, CH3, CF3, aryl, heteroaryl, C1-C4 alkylaryl or C1-C4 alkylheteroaryl, for use as inhibitors of the DPP-IV enzyme in the treatment or prevention of conditions including Type II diabetes.