A method for preventing and/or treating a metabolic disease, cerebrovascular disease, etc. which comprises administering to a mammal an effective amount of the compound of the formula (I): wherein all symbols have the same meanings as defined in the specification; a salt thereof, an N-oxide thereof, a solvate thereof, or a prodrug thereof. And a novel compound of the formula (I-1): wherein all symbols have the same meanings as defined in the specification; a salt thereof, an N-oxide thereof, a solvate thereof, or a prodrug thereof has an anti-diabetic effect and a neuroprotective effect. Accordingly, the compound of the formula (I) and the compound of the formula (I-1) are useful in a method for preventing and/or treating for a metabolic disease such as diabetes, cerebrovascular disease such as stroke, etc.