Plasma insulin and surgery. I. Early changes due to operation in the insulin response to glucose

The effects of elective abdominal operation on the disposal of a sustained intravenous glucose load and on the biphasic response of plasma insulin have been examined. During operation, low plasma insulin concentrations were observed despite the high plasma glucose values achieved. On the morning after operation, both phases of the insulin response to glucose were increased. This increase was seen even when subjects were compared at the same plasma glucose value. The response to tolbutamide was also greatly exaggerated. Pre- and postoperative glucose curves were approximately parallel, suggesting that glucose uptake was similar in both situations despite the presence of the postoperative hyperglycemia and hyperinsulinemia. This is at variance with previous reports based on conventional bolus dose intravenous tests which have suggested reduced postoperative glucose utilization. A new interpretation of the data is proposed.