The use of dietary fiber (DF) in the diet of diabetics, although recommended, is often prevented by a limited tolerance and/or by the high cost and unpalatability of fiber supplements. Knowing that only or mainly the water soluble fraction of DF is effective in modulating postprandial hyperglycemia, the DF content (soluble, insoluble, and total) of a variety of common foodstuffs was determined. Such data were then utilized in the formulation of two complete meals, isocaloric and isoglucidic, characterized by a high-soluble, low-soluble, and total fiber content. The meals were administered to 13 NIDDM patients in good metabolic control. The data confirmed a significant reduction (p less than 0.001) of postprandial hyperglycemia and a moderate less significant reduction of insulinemia after the high fiber meal.