Plasma Insulin Concentrations in Dogs and Monkeys After Xylitol, Glucose or Tolbutamide Infusion

Beagle dogs and Rhesus monkeys were infused with xylitol, glucose, or tolbutamide at intervals of ten to fourteen days. Infusion of all three agents produced significant increases in mean plasma insulin concentrations in both species. In dogs, xylitol produced the highest insulin concentrations followed by glucose and tolbutamide in that order, while in monkeys, glucose produced the highest insulin concentrations followed by tolbutamide and xylitol. The insulinotropic effect of both xylitol and glucose in the monkey was abolished by simultaneous infusion of epinephrine. Results suggest that glucose and xylitol stimulate release of insulin through a common metabolite of the pentose phosphate pathway. However, unexplained quantitative differences exist between the monkey and dog with respect to the insulinotropic response to these agents.