Insulin Secretion in Acromegaly

A comparative study of insulin release was made in 9 acromegalic and 39 normal subjects who had normal fasting plasma glucoses. Both hyperglycemic (increase of plasma glucose of at least 25 mg/100 ml) and nonhyperglycemic stimuli were used. Those producing hyperglycemia included a 100 g oral glucose tolerance test and a glucose-protein meal. Those not producing hyperglycemia were a protein meal and an arginine infusion. Nondiabetic acromegalic patients responded to every stimulus investigated with hyperinsulinism. Decreased carbohydrate tolerance was present only in the glucose tolerance test. Carbohydrate intolerance alone was not sufficient even in the glucose tolerance test to account for increased insulin secretion (I/G ratios are significantly greater than normal).