Pharmaceutical compositions for the prevention or treatment of diabetes, containing as the active ingredient compounds represented by the general formula (I), or pharmacologically acceptable salts, esters, or other derivatives thereof: (I) wherein A is benzene, pyridine, pyridazine, pyrimidine, pyrrole, furan, thiophene, pyrazole, imidazole, isoxazole, or isothiazole, each being optionally substituted; R<sp>1</sp> is aryl or heteroaryl, each being optionally substituted; R<sp>2</sp> is optionally substituted nitrogenous heteroaryl; and R<sp>3</sp> is a mono− or poly−cyclic nitrogenous heterocycle which may be substituted, with the proviso that the A−constituent atoms to which R<sp>1</sp> and R<sp>3</sp> bonded are each adjacent to the A−constituent atom to which R<sp>2</sp> is bonded.
