A remedy for diabetes mellitus characterized in that it contains L-arabinose and sucrose (sugar or sugar-containing food or beverage) as effective ingredients. A food or beverage for improvement of diabetes mellitus characterized in that it contains L-arabinose and sucrose (sugar or sugar-containing food or beverage) as effective ingredients. A method for using L-arabinose characterized in that, for the treatment of diabetes mellitus, L-arabinose is taken together with or prior to ingestion of sucrose (sugar or sugar-containing food or beverage).