Somatostatin does not cause sustained fasting hyperglycemia in man

Somatostatin inhibits both insulin and glucagon secretion; its short-term infusion causes a transient decrease in plasma glucose followed by modest hyperglycemia in man, suggesting that insulin deficiency per se is sufficient to cause fasting hyperglycemia. If this is true, then prolonged inhibition of insulin secretion should result in persistent and more progressive hyperglycemia. On the other hand, if glucagon modifies the metabolic consequences of insulin deficiency, then prolonged inhibition of secretion of both insulin and glucagon might not result in sustained hyperglycemia. To examine these alternatives, changes in plasma glucose, insulin and glucagon, as well as glucose turnover and glucose balance during prolonged infusions of somatostatin (for 12 hr) were studied.