The present invention provides nitrogen-containing fused-ring derivatives represented by the following general formula, or pharmaceutically acceptable salts thereof, or prodrugs thereof, which exhibit an excellent inhibitory activity in human SGLT and are useful as agents for the prevention or treatment of a disease associated with hyperglycemia such as diabetes, postprandial hyperglycemia, impaired glucose tolerance, diabetic complications or obesity, in the formula R.sup.1 represent H, an optionally substituted alkyl group, analkenyl group, etc.; R.sup.2 represent H, a halogen atom or an alkyl group; R.sup.3 and R.sup.4 represent H, OH, a halogen atom, an optionally substituted alkyl group, etc.; Y represents CH or N; Q represents alkylene, alkenylene, etc.; ring A represents an aryl group or a heteroaryl group; G represents a group represented by the following general formula (G-1) or (G-2) (in which E.sup.1 represents H, F or OH; and E.sup.2 represents H, F, a methyl group, etc.), and pharmaceutical compositions comprising the same, and pharmaceutical uses thereof ##STR00001##