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.本發明為提供一種安全且具有優良糖代謝改善作用之糖代謝改善劑,及安全且具有優良GLP-1分泌促進用之GLP-1分泌促進劑。本發明係將特定環狀二肽或其鹽作為有效成分。本發明之糖代謝改善劑或GLP-1分泌促進劑具有優良糖代謝改善作用之同時,亦具有可安全且長期間攝取之優點。
