THE TOLERANCE OF NORMAL SUBJECTS TO LEVULOS E

Abstract

Levulose tolerance tests (91) and 12 glucose tolerance tests were performed on normal subjects under a variety of conditions. Results have been tabulated according to the fasting blood sugar level with the following conclusions: In normal subjects the maximum blood sugar following administration of 30-50 gm. (based on body weight) of levulose by mouth rarely exceeds 115 mgm. %. A rise in blood sugar to 125 mgm. % or over should be considered an abnormal response to the oral administration of levulose. In the group of convalescent subjects included in this study the levulose tolerance was the same as in the normal subjects studied. Triplicate levulose tolerance tests performed on normal subjects 7 or more days apart show no significant variation in their blood sugar curves. In normal subjects the rise in blood sugar above the fasting level following the oral administration of levulose varies inversely with the height of the fasting blood sugar level. It seems probable that there is a level of blood sugar varying from 95 to 110 mgm. %, which when exceeded stimulates the sugar storage mechanism to clear the blood rapidly of its excess sugar. A period of 10-15 min. elapses after this excitatory ceiling is reached before the sugar storage mechanism begins to cause a significant fall in blood sugar. The rise in blood sugar above this level depends upon the rapidity of absorption of the sugar administered. The rapidity with which the blood sugar falls from its peak probably depends upon the glycogen forming ability of the sugar tested.