Plasma Insulin and Surgery II Later Changes and the Effect of Intravenous Carbohydrates

Abstract

Long-term hyperinsulinemia and improved glucose tolerance were produced postoperatively by i.v. feeding with glucose or sorbitol. Raised immunoreactive insulin (IRI) values persisted 8 h after carbohydrate infusions although the basal plasma glucose concentrations had returned to control values. Plasma glucose curves were normal at this time but were associated with an increased IRI response. These findings suggest that insulin secretion is modified by glucose not only in the short term but also by a separate effect acting over many hours. The combination of starvation and low dose glucose infusion to simulate the hyperglycemia of operation also produced high IRI values but these were associated with a rapid fall in the plasma glucose curve. Starvation alone reduced basal values of plasma glucose and IRI and the IRI response to glucose infusion was also reduced, despite the plasma glucose curve being at a higher level. The high values of IRI reported in the postoperative period are probably mediated by a long-term effect of the small but sustained rise in basal plasma glucose. This specific role of glucose in the long-term potentiation of insulin secretion make it the carbohydrate of choice for the i.v. feeding in postoperative patients.