To verify the benofit of nonglucose carbohydrates and fiber in enteral formula diets we studied the postprandial metabolism of eight healthy subjects after the intake of two helpings (25 g carbohydrates each) of five commonly used enteral formulas over 4 h. There were no significant differences in postprandial concentrations of blood glucose among the formulas. The area under the curve of postprandial insulin values, however, was significantly smaller after consumption of the fructose-containing formula (]948_+2851xUmin m1-1, P<0.05) than after fiber-free (3222_+ 678 gU min m1-1) or two fiber-containing products (2664__ 326 gU min ml-1, p < 0.05 ; and 3040_+ 708 gU rain ml -1, p < 0.05). The insulin area of the xylitol-containing formula (2307 _+ 364 gU min m1-1) was significantly smaller compared to the fiberfree product (P< 0.05). In addition, we found the postprandial increase in triglycerides to be significantly higher after the xylitol-containing formula (from 0.93+0.14 to 1.25_+0.22mmol/1) than after the fiber-free product (from 0.82-t-0.13 to 0.97+0.16mmol/1, P<O.05) or the two fibercontaining products (from 0.88_+0.16 to 0.96_+ O.18mmol/1, P<O.05; and from 0.80+0.08 to 0.95_+0.10 mmol/1, P<O.05). We conclude that a patient with type II diabetes may benefit from replacing glucose and glucose-equivalent carbohydrates with fructose or xylitol.