In diabetic patients, compliance to diet therapy has been an ongoing concern. We thus examined the effects of an aspartame-and acesulfame K-containing sweetener (PZ) on postprandial hyperglycemia in mild and borderline diabetics. In two sets of crossover, randomized, placebo-controlled, double-blind tests, subjects with mild or borderline diabetes were challenged with meals consisting of white rice, and two side dishes flavored with PZ (PZ meal) or sugar (Control meal); or with sweets flavored with PZ (PZ sweets) or sugar (Control sweets). The use of PZ (PZ meal and PZ sweets) significantly reduced postprandial levels, particularly at 1 h, of blood glucose and insulin when compared to sugar (Control meal and Control sweets). The results demonstrated that PZ as a sugar substitute enabled the suppression of postprandial hyperglycemia in mild or borderline diabetics without compromising palatability, sweetness or patient QOL.