The present invention relates to compounds, which are useful for treatment and/or prevention of diabetes mellitus, diabetes mellitus complications or obesity, since the compounds have glucokinase-activating effects, and are presented in Formula (I): wherein R1 represents a carbamoyl group； R2 represents a lower alkyl group； both of X1 and X2 represent CH, or any one of X1 and X2 represents a nitrogen atom and the other represents CH； a group of represents a group selected from the group consisting of a pyridinyl, a pyrazinyl, a pyrazolyl, a thiadiazolyl, a triazolyl, an isoxazolyl and a thiazolyl group； and k is zero or 1, or relates to pharmaceutically acceptable salts thereof.
