On the relation of glucose and insulin secretion in the fasting state.

In the isolated perfused rat pancreas the relationship between glucose concentration and insulin release was altered by fasting for 1-3 days. The maximum effect decreased progressively, while there was no change in the glucose concentration, yielding half of maximum response. Prolonged perfusion of the pancreas from fasting rats with glucose (20 mM) failed to restore the reduced secretion. The insulin content of the pancreas gland decreased after the second day of starvation. Blood glucose, however, was unchanged for 4 days after an initial fall. It is concluded that the capacity of the secretory mechanism, rather than its sensitivity to glucose, is reduced by starvation.