Xylitol, a partial homologue ot alpha-D-glucopyranose: potent stimulator of insulin release in dogs.

A direct comparison was made in healthy female dogs of the potency of xylitol and mutarotated glucose as stimulators of insulin release (both first and second phases), and also of their urinary excretion and arterio-venous difference across a hind-limb. Xylitol or glucose was given by constant infusion into a systemic vein for 50 minutes in paired experiments. Three dose levels were used in 12 dogs. Plasma insulin levels during xylitol infusion were as high as or higher than those during glucose infusion, with increases in arterial xylitol levels equal to or less than those in glucose. More xylitol was lost in the urine, but the overall uptake of xylitol was at least 70% also the arteriovenous difference for xylitol across the hind-limb was greater than for glucose, when each was divided by the arterial sugar concentration. It is suggested that both the striking potency of xylitol in stimulating both phases of insulin release, and its rapid uptake by tissues, may result from its homology with alpha-D-glucopyranose, the alpha-anomer of glucose. The concept of a glucoreceptor on the surface of the pancreatic beta-cell, with stereospecificity for alpha-D-glucopyranose or closely similar molecules, is supported by our results.