An alkanoic acid derivative useful as a prophylactic or therapeutic agent of diabetes mellitus, hyperlipidemia, impaired glucose tolerance and the like can be provided by a compound represented by the formula ##STR00001## wherein R.sup.1 is an optionally substituted 5-membered aromatic heterocyclic group; X is a bond and the like; Q is a divalent hydrocarbon group having 1 to 20 carbon atoms; Y is a bond and the like; ring A is an aromatic ring optionally further having 1 to 3 substituents; Z is --(CH.sub.2).sub.n-Z.sup.1-(n is an integer of 1 to 8 and Z.sup.1 is an oxygen atom and the like) and the like; ring B is a pyridine ring optionally further having 1 to 3 substituents, and the like; U is a bond and the like; W is a divalent hydrocarbon group having 1 to 20 carbon atoms; and R.sup.3 is --OH and the like, provided that, when ring B is a benzene ring optionally further having 1 to 3 substituents, U should be a bond, or a salt thereof.