Disclosed is a compound having an anti-hyperglycemic activity, which is useful for the treatment or prevention of diabetes, obesity and others. Specifically disclosed is a compound represented by general formula (1) [wherein R1 and R2 independently represent a hydrogen atom, a halogen atom, an amino group, a hydroxy group, a hydroxyamino group, an nitro group, a cyano group, a sulfamoyl group, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C1-C6 alkylsulfanyl group, a C1-C6 alkylsulfinyl group, a C1-C6 alkylsulfonyl group or a (C1-C6 alkoxy)-(C1-C6 alkylsulfonyl) group; and A represents a heteroaryl group which may have a substituent] or a pharmaceutically acceptable salt thereof.