Immunoreactive Insulin in the Portal and the Peripheral Venous Blood after Intravenous Tolbutamide Administration

Immunoreactive insulin has been assayed in portal and peripheral venous blood in fourteen patients with hepatic, pancreatic and gastric disease before and after tolbutamide administration. The difference between portal and peripheral insulin varied considerably in different patients. In some of the patients the portal insulin seemed to increase at a time when peripheral venous insulin had started to decrease. The implication of this finding is discussed.