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.
