The present invention relates to novel compounds of formula (I) and their pharmaceutically acceptable salts, wherein ring "Ar.sub.1" represents a monocyclic or polycyclic aromatic or partially saturated aromatic polycyclic, which may optionally contain up to 3 heteroatoms selected from N, S or O. The said monocyclic or polycyclic ring may be unsubstituted or have up to 4 substituents which may be identical or different; m and n independently represents an integer from 0 to 6; A represents O, S or bond; Y is selected from (CH.sub.2).sub.p'(CH.sub.2).sub.pB(CH.sub.2).sub.q'(CH.sub.2).sub.rB(CH.s- ub.2).sub.pD(CH.sub.2).sub.p' where p, q and r each independently represents an integer from 0 to 6; B and D independently represents S, O, NR.sup.4 or a bond, with a proviso that when B and D represents hereto atom p is not zero; R.sup.4 represents hydrogen, alkyl, alkenyl, --S(O).sub.2--R.sup.8 or --C(O)R.sup.8 where R.sup.8 is alkyl, alkoxy; R.sup.5 and R.sup.6 independently represents hydrogen, alkyl, cycloalkyl or alkoxy; R.sup.5 and R.sup.6 together may form 3-8 membered cyclic ring which may optionally contains one or two hereto atoms selected from O, S or N; R.sup.7 represents hydrogen, optionally substituted groups selected form alkyl, cycloalkyl, alkenyl or alkynyl. The present invention also relates to a process for preparation of compounds of formula (I), to pharmaceutical compositions containing compounds of formula (I) and their use in particular as antidiabetic, hypolipidemic, antiobesity and hypocholesterolemic agents.