Provided is a composition having an excellent physiological effect. Inventors have found that a composition in which the total amount of cyclic dipeptides including amino acids as constituent units, or salts thereof, is greater than or equal to a specific amount has the effect of improving sugar metabolism, and have also found that the sugar metabolism improvement effect is achieved by including given contents of specific cyclic dipeptides. This composition is advantageous in that it has an excellent sugar metabolism improvement effect, and that it can be taken in safely for a long period of time.本發明之課題為提供一種具有較佳生理作用之組成物。作為解決手段，本發明者發現在將胺基酸作為構成單位之環狀二肽或其鹽的總量為特定量以上之高含量的組成物中具有改善糖代謝之作用。進一步發現，藉由包含一定含量之特定環狀二肽，能夠更加發揮糖代謝改善作用。本發明組成物在具有優異之糖代謝改善作用的同時，也具有能夠安全且長時間攝取的優點。
