A novel use of D-psicose (for suppressing the abnormal intra-day increase of blood glucose level) is provided. A composition containing D-psicose as the active component and for use in suppressing the abnormal intra-day increase of plasma glucose concentration. The composition is a composition in blend with D-psicose and/or a derivative thereof. The composition is in a form selected from sweeteners, seasonings, food additives, food materials, food and drink products, health food and drink products, pharmaceutical products, and feeds and blended with D-psicose, and/or a derivative thereof as the active component, for use in preventing and therapeutically treating diseases requiring the saving of insufficient insulin, the amelioration of insulin sensitivity and the amelioration of hyperglycemia, and/or diseases of which the symptoms can be ameliorated via the suppression of the abnormal intra-day increase of plasma glucose concentration or of which the onset can be prevented via the suppression thereof, such as diabetes mellitus, occult diabetic states, obesity, hyperglycemia, and/or arteriosclerosis. A method for using D-psicose in suppressing the abnormal intra-day increase of plasma glucose concentration, comprising giving D-psicose at given times to suppress the abnormal increase of plasma glucose concentration throughout the day.