Provided is a safe carbohydrate metabolism-ameliorating agent having an excellent carbohydrate metabolism-ameliorating action, and a safe GLP-1 secretion accelerator having an excellent GLP-1 secretion-accelerating action. The carbohydrate metabolism-ameliorating agent or GLP-1 secretion accelerator according to the present invention, which contains a specific cyclic dipeptide or a salt thereof as an active ingredient, is advantageous in that it has an excellent carbohydrate metabolism-ameliorating action, and that it is safe and can be ingested for a long period.
