Influence of Antecedent Carbohydrate Intake on the Biphasic Insulin Response to Intravenous Glucose

The insulin secretory response to a sudden and sustained intravenous glycemic stimulus was measured in three groups of dogs whose antecedent carbohydrate intake ranged from zero to 300 or more grams daily. Insulin outflow rate from the pancreaticoduodenal vein was measured every minute for ten minutes, then at increasing intervals through sixty minutes. It was found that starvation erased the first phase of the biphasic insulin response shown by dogs on ordinary carbohydrate intake and that high-carbohydrate intake abolished the trough between the two phases. The data suggest that, during truly physiologic stimulation of insulin secretion, the latter represents the final stage of a continuum of hormonal synthesis, storage, and release, rather than emanating from one of two separate pools of fast-versus-slow insulin secretion.