Provided are a safe glucose metabolism ameliorating agent having an exceptional glucose metabolism ameliorating effect, and a safe GLP-1 secretion accelerator having an exceptional GLP-1 secretion accelerating effect. The active ingredient is a specific cyclic peptide or salt thereof. The glucose metabolism ameliorating agent or GLP-1 secretion accelerator according to the present invention is advantageous in terms of being safe and able to be taken over an extended period of time, together with having an exceptional glucose metabolism ameliorating effect.