Thirty-four subjects were categorized on the basis of their glucose tolerance as normal (thirteen subjects), probable diabetics (six subjects), mild diabetics (five subjects), tolbutamide-responsive diabetics (five subjects) and insulin-dependent diabetics (five subjects). Fifteen grams of d-ribose dissolved in six ounces of water were administered orally to each of the subjects and the effect on serum glucose concentration was measured. The hypoglycemie effect of d-ribose varied in an orderly and progressive manner through the different categories of glucose intolerance. As their glucose intolerance increased in severity, the subjects were significantly less responsive to the blood glucose lowering effect of d-ribose.
The serum immunoreactive insulin concentration in response to the oral administration of d-ribose was measured in the normal and mild diabetic subjects. The mild diabetics had a mean peak increase in immunoreactive insulin which was 2.6-fold greater than the normal subjects; however, the insulin concentrations attained were not significant in either group. Thus the insulinogenic response as determined in peripheral venous blood does not account for the differential hypoglycemie effect of d-ribose.