The invention relates to compounds of formula Z-C(R.sup.1R.sup.2)--C(R.sup.3NH.sup.2)--C(R.sup.4R.sup.5)-A (I) wherein Z, R --R and A have the meaning as cited in the description and the claims as examplified by the compound (II) said compounds are useful as DPP-IV inhibitors. The invention also relates to the preparation of such compounds as well as the production and use thereof as medicament.