Plasma Glucose Disappearance

minute. Under basal conditions, 2.64+0.28 (mean±SEM) mU/min m2 reaches the systemic circulation. In the 90 min that follow acute glucose stimulation, 0.86+0.11 U/M2, a 270% increment over the basal production rate, is made available to the periphery. A wide individual variability was found to exist in both the basal and the glucose-stimulated delivery. They were strongly (P < 0.001) related to each other in a direct fashion. A first spike of insulin release (107+12 mU/min) occurred in all the subjects at 2.2+±0.2 min followed, in 16 subjects, by a second spike (38+6 mU/min), at 11.3+0.9 min. Two-thirds of the total postglucose insulin output were associated with the initial, oscillatory phase (from 0 to 25 min, on average), and one-third with the "tail" phase (from 25 to 90 min), during which the average delivery rate was 5.0+0.9 mU/min m2. The delivery curves were closely (mean squared deviation of4.5+0.5 mU/min) reproduced by computer simulation upon assuming that insulin secretion is a function ofboth glucose concentration and glucose rate of change. Received for publication 11 April 1978 and in revised form 5 March 1979. Both the first and the second spike ofinsulin delivery, but not the total insulin output during the test, showed a significant, positive correlation with the plasma glucose disappearance rate computed between 10 and 60 min. Furthermore, with a time shift of -15 min, a significant relationship between the phases of insulin secretion and the glucose decay rates, computed over corresponding time intervals, was evident throughout the test.