A nitrogenous fused-ring derivative represented by the following general formula (I), a pharmacologically acceptable salt thereof, or a prodrug of either. They have human SGLT inhibitory activity and are useful as a preventive or therapeutic agent for diseases attributable to hyperglycemia, such as diabetes, postprandial hyperglycemia, impaired glucose tolerance, complications of diabetes, and obesity. [In the formula (I), one of R<1> and R<4> represents a group represented by the following general formula (S) (wherein R<5> and R<6> each represents H, OH, halogeno, etc.; Q represents alkylene, etc.; and ring A represents aryl, etc.) and the other represents H, OH, amino, etc.; R<2> and R<3> each represents H, OH, amino, halogeno, optionally substituted alkyl, etc.; A<1> represents O, S, etc.; A<2> represents CH or N; and G represents a group represented by the following general formula (G-1) (wherein E<1> is H, F, or OH and E<2> represents H, F, methyl, etc.) or the group represented by the following general formula (G-2). |