Glucose Homeostasis (12)

During rewarming, plasma insulin increased twofold over preoperative values. Similar findings were reported by Baum et al. This rebound could be due to a hypersecretion of insulin after a reduced release during hypothermia. The concomitant increase in glycemia is explained by the action of hyperglycemic hormones, particularly glucagon which increased simultaneously and has a rapid effect.
At the third postoperative hour, plasma insulin increased by 127 percent over initial values after hypothermic CPB. Because no significant change was observed after normothermic CPB, it could be suggested that hypothermic CPB induces insulin resistance. This may explain the parallel changes in blood glucose and insulin levels during and after hypothermic CPB.
As in the present study, Kuntschen et al observed no change in plasma glucagon levels during hypothermic CPB and higher concentrations during normothermic CPB. In addition, a glucagon injection did not increase blood glucose during hypothermic CPB. In our hypothermic group, rewarming elicited glucagon secretion so that plasma concentrations were transiently similar in the two groups at the end of CPB.