Comparative insulinogenic effects of glucose, arginine and glucagon in patients with diabetes mellitus, endocrine disorders and liver disease.

Abstract

In order to compare the insulinogenic effects of glucose, arginine and glucagon, plasma immunoreactive insulin levels following oral glucose loading (50 g), intravenous arginine infusion (30 g for 45 min) and intravenous glucagon injection (1 mg) were determined in patients with diabetes mellitus, various endocrine diseases and chronic hepatitis. In patients with Cushing’s syndrome, plasma insulin responses to all three stimuli were exaggerated, whereas they were low in patients with pheochromocytoma. In other diseases, certain disparities were observed in plasma insulin responses. In patients with mild diabetes mellitus, insulin secretion elicited by glucose seems to be selectively impaired, because arginine and glucagon caused a rise in plasma insulin not significantly different from that in normal subjects. In patients with hyperthyroidism, plasma insulin responses to arginine and glucagon were either absent or limited, although rather a exaggerated response was noted following oral glucose loading. On the contrary, exaggerated responses to arginine and glucagon, and limited response to glucose were observed in hypothyroidism. In patients with chronic hepatitis, the responses of plasma insulin to glucose and arginine were both exaggerated, whereas the response to glucagon was comparable to that in normal subjects. These disparate responses suggest that glucose, arginine and glucagon act on the B-cell via different mechanisms.