CONDENSED RING PYRAZINE DERIVATIVE

PROBLEM TO BE SOLVED: To obtain an insulin secretion-promoting agent that has the glucose concentration-depending insulin secretion-promoting action and a suitable blood sugar-decreasing action and is useful in the treatment of diabetes, by using a specific condensed ring pyrazine derivative as an active ingredient. SOLUTION: This compound is a condensed ring pyrazine derivative represented by the formula [R1A and R1B are each H or a lower alkyl; R is H or a (substituted)lower alkyl; X1-X4 are each CH or N; m and n are each 0 or 1; W...V...U is N-C=O, N=C-N; when W...V...U is N-C=O, Y...Z is CH-CH2 or the like; R2 is a (substituted) cycloalkyl or the like; when W...V...U is N=C-N, Y...Z is C=CH, R3A and R3B are each a (substituted)aryl or the like] or its pharmaceutically acceptable salt, typically 1-methyl-3-(2- oxophenetyl)-3,4-dihydro-1H-quinoline-2-one or the like. The compound is used as an active ingredient and is orally or parenterally administered in the does of 1-1,000 mg/time, once a day.