The Effect of Insulin on the Glucose Tolerance of Normal Man.

Utilization of carbohydrate by the diabetic patient probably differs only quantitatively from that of the normal subject. Many factors which influence carbohydrate tolerance in normal subjects (for example, exercise, emotional disturbances, infections, and the nature of the preceding diet) do likewise in diabetic patients. Any measure which affects the tolerance of the normal subject for carbohydrate merits investigation for its applicability to the treatment of diabetes. The administration of insulin to non-diabetic subjects may provoke diabetic responses to glucose tolerance tests. This has been observed in obese (1), undernourished (2, 3), and psychotic (4) patients. In the present experiments, in an attempt to elucidate this phenomenon, the effect of small doses of crystalline and protamine insulin on the respiratory metabolism, as well as on the conventional glucose tolerance test, of normal man has been investigated.