Compounds which are 1-(2'-aminoacyl)-2-cyanopyrrolidine derivatives according to general formula (1) are DP-IV inhibitors for treatment of impaired glucose tolerance or type 2 diabetes; wherein A is selected from groups (2, 3 and 4); X is selected from aminoacyl groups corresponding to the natural amino acids, acyl groups R.sup.3CO, groups R.sup.4COOC(R.sup.5)(R.sup.6)OCO, methoxycarbonyl, ethoxycarbonyl and benzyloxycarbonyl; R.sup.1 is selected from H, C.sub.1 C.sub.6alkyl residues, (CH.sub.2).sub.aNHW.sup.1, (CH.sub.2).sub.bCOW.sup.2, (CH.sub.2).sub.cOW.sup.3, CH(Me)OW.sup.4, (CH.sub.2).sub.d--C.sub.6H.sub.4--W.sup.5 and (CH.sub.2).sub.eSW.sup.6, where a is 2 5, b is 1 4, c is 1 2, d is 1 2, e is 1 3, W.sup.1 is COW.sup.6, CO.sub.2W.sup.6 or SO.sub.2W.sup.6, W.sup.2 is OH, NH.sub.2, OW.sup.6 or NHW.sup.6, W.sup.3 is H or W.sup.6, W.sup.4 is H or W.sup.6, W.sup.5 is H, OH or OMe, and W.sup.6 is C.sub.1 C.sub.6 alkyl, optionally substituted phenyl, optionally substituted heteroaryl or benzyl and R.sup.2 is selected from H and (CH.sub.2).sub.n--C.sub.5H.sub.3N--Y, where n is 2 4 and Y is H, F, Cl, NO.sub.2 or CN, or R.sup.1 and R.sup.2 together are --(CH.sub.2).sub.p-- where p is 3 or 4; R.sup.3 is selected from H, C.sub.1 C.sub.6 alkyl and phenyl; R.sup.4 is selected from H, C.sub.1 C.sub.6 alkyl, benzyl and optionally substitued phenyl; R.sup.5 and R.sup.6 are each independently selected from H and C.sub.1 C.sub.6 alkyl or together are --(CH.sub.2).sub.m--, where m is 4 6; R.sup.7 is selected from pyridyl and optionally substituted phenyl; R.sup.8 is selected from H and C.sub.1 C.sub.3 alkyl; and R.sup.9 is selected from H, C.sub.1 C.sub.6 alkyl, C.sub.1 C.sub.6 alkoxy and phenyl. ##STR00001##