Attempting to maintain normoglycemia during cardiopulmonary bypass with insulin may initiate post-operative hypoglycemia

Abstract

Cardiopulmonary bypass is known to cause alterations in insulin secretion and resistance, resulting in profound hyperglycemia. Aggressive treatment of the resulting hyperglycemia intra-operatively could result in a severe degree of post-operative hypoglycemia. We undertook this prospective non-randomized clinical study to compare the alterations in glucose homeostasis in diabetic (group A, n=50) and non-diabetic (Group B, n=50) patients undergoing moderate hypothermic (30°C) cardiopulmonary bypass for coronary artery bypass grafting (CABG). All patients had a fasting blood sugar level done on the morning of surgery. Blood sugars were monitored intra-operatively and post-operatively at fixed time intervals. Intra-operative hyperglycemia was treated aggressively by a continuous, infusion of injecting plain insulin. Both the groups experienced similar significant increase in blood glucose levels during bypass (‘p’=0.00003). However, the mean blood glucose level upon arrival in the intensive care unit was significantly decreased in group B compared to group A (p=0.0002). 60% of group B and 10% of group A patients required treatment for post-operative hypoglycemia (blood glucose level <60mg/dl). This clinical study reveals that attempting to maintain normoglycemia in this setting with Insulin may initiate post-operative hypoglycemia.