Abstract: This invention relates to 4-formyl-2-(naphthalenylmethyl)phenoxyacetic acids and pharmaceutically acceptable salts thereof according to formula I below, pharmaceutical compositions thereof, a method of treating hyperglycemia due to non-insulin dependent diabetes mellitus, and a method of prevention or treatment of complications associated with diabetes. ##STR1## wherein the group A is selected from the group consisting of 1-naphthyl, 2-naphthyl, optionally substituted with alkyl of from one to six carbon atoms, fluorine, chlorine, bromine, iodine, trifluoromethyl, alkoxy of from one to six carbon atoms; R.sup.1 is hydrogen or alkyl of from one to six carbon atoms; R.sup.2 is selected from hydrogen, fluorine, chlorine, bromine, iodine, alkyl of from one to six carbon atoms, alkoxy of from one to six carbon atoms, and hydroxyl; or a pharmaceutically acceptable metal salt thereof.