The invention provides a composition used for promoting glucose uptake, which comprises a peptide having an effect of promoting glucose uptake as the active ingredient, as well as a composition comprising a dipeptide containing leucine and/or isoleucine as the active ingredient. The composition is effective in preventing or treating diabetes mellitus or an elevation of blood glucose level, in promoting glycogen storage, or in enhancing physical strength, enhancing athletic ability, improving endurance performance or relieving fatigue.
