Suppression and Stimulation Mechanisms Controlling Glucagon Secretion in a Case of Islet-Cell Tumor Producing Glucagon, Insulin, and Gastrin

The mechanisms controlling secretion of glucagon and other pancreatic hormones were studied in a patient affected with multihormone-secreting islet-cell tumor.

Fasting glucagon levels (3,000 pg./ml.) rose to 10 ng./ml. following arginine stimulation. While oral glucose load and intravenous glucose infusion did not suppress glucagon secretion, insulin administration induced a prompt depression in glucagon levels. Glucagon, insulin, and gastrin levels were suppressed by somatostatin while calcium infusion caused a paradoxical increase.

It is suggested that only some of the stimulation-inhibition mechanisms were conserved in this case of glucagon-secreting pancreatic tumor.