To what extent does increased dietary fiber improve glucose and lipid metabolism in patients with noninsulin-dependent diabetes mellitus (NIDDM)?

The present study assesses the impact of variations in the amount of fiber in high carbohydrate diets on carbohydrate and lipid metabolism in NIDDM. The amount and source of carbohydrate, and source of dietary fiber, were held constant. Two 4-wk diet periods were randomly assigned and all subjects completed both dietary periods. Diets were identical in the proportion of carbohydrate, fat, protein, P/S ratio, and cholesterol. The normal fiber diet contained 11 g/1000 kcal, while the high fiber diet contained 27 g/1000 kcal. The results showed no significant difference in fasting plasma glucose and insulin, day-long glucose and insulin, fasting hemoglobin AIc, or 24 h urinary glucose. Fasting plasma triglyceride and VLDL-triglyceride, as well as fasting plasma cholesterol, LDL-cholesterol, and HDL-cholesterol were also unchanged. In conclusion, an increase in the fiber content from 11 to 27 g/1000 kcal did not lead to measurable improvements in overall plasma glucose, insulin, or lipid metabolism.