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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.

The present investigation was carried out in 16 healthy subjects in order to study whether calcium antagonism would affect the hypoglycemic response to insulin, and/or whether it would affect the insulin and glucose responses to glucagon. For this purpose verapamil, a potent calcium-blocking agent, was used. Verapamil infused alone did not affect the basal insulin or glucose concentrations. However, such infusion reduced the hypoglycemic response to insulin. Furthermore, the glucose response to glucagon was augmented by simultaneous infusion of verapamil, whereas the insulin response to glucagon was unaffected. When healthy volunteers were simultaneously infused with both calcium and verapamil the glucose response to glucagon was no longer augmented. The insulin response to glucagon also remained unaffected. These findings indicate that intravenous verapamil has hyperglycemic effects, unrelated to insulin, under certain conditions. They also imply that exogenous hypercalcemia counteracts the augmentative effect of verapamil on the glucose response to glucagon.