The present invention is related to compounds represented by the following formula, or salts or hydrates thereof ##STR00001## wherein, T.sup.1 represents a 4- to 12-membered heterocyclic group containing one or two nitrogen atoms in the ring, which is a monocyclic or bicyclic structure that may have one or more substituents; X represents a C.sub.1-6 alkyl group which may have one or more substituents, or such; Z.sup.1 and Z.sup.2 each independently represent a nitrogen atom or a group represented by the formula --CR.sup.2--; R.sup.1 and R.sup.2 independently represent a hydrogen atom, a C.sub.1-6 alkyl group which may have one or more substituents, or a C.sub.1-6 alkoxy group which may have one or more substituents, or such. These are novel compounds that exhibit an excellent DPPIV-inhibiting activity.