Augmentation of Insulin Secretion by a Non-Nutrient Drink

Abstract

Because it is known that nutrients can enhance insulin release, we studied the effect of a drink which was devoid of nutrients upon the immunoreactive insulin response to i.v. glucose in 13 normal subjects. The summated immunoreactive insulin secretory response during an i.v. glucose infusion (500 ml 10% glucose over 30 min) was 178 +/- 32 (SEM) microU/ml. However, when subjects ingested 500 ml 3% mannitol in a physiologic electrolyte solution given 30 min before the i.v. glucose, 56% augmentation of insulin release was noted (277 +/- 38 microU/ml, P less than 0.005). Post-infusion serum glucose was lower when the drink preceded i.v. glucose. The 3% mannitol-electrolyte drink itself did not significantly alter insulin, gastrin, gastric inhibitory polypeptide, or glucagonlike immunoreactivity. Two percent mannitol-electrolyte solution did not produce the insulin enhancing effects of the more hypertonic solution. In contrast with the effects of glucose, when arginine was used as the i.v. insulin secretagogue, antecedent 3% mannitol-electrolyte ingestion produced no enhancement of insulin release. This study demonstrates that ingestion of a non-nutrient drink with an osmolality of at least 456 mosmol/kg augments insulin secretion in response to a subsequent i.v. glucose load.