Dynamic changes in insulin requirements with post-operative time using bedside artificial pancreas to maintain normoglycemia without hypoglycemia after cardiac surgery

It is difficult to manage postoperative blood glucose levels without hyperglycemia and hypoglycemia in cardiac surgery patients even if continuous intravenous insulin infusion is used. Therefore, the insulin requirements for maintaining normoglycemia may be difficult to evaluate and need to be elucidated. In this single-center retrospective study, 30 adult patients (age 71.5 ± 9.0 years old, men 67%, BMI 22.0 ± 3.1 kg/m², diabetes 33%) who underwent cardiac surgery and used bedside artificial pancreas (STG-55) as a perioperative glycemic control were included. We investigated the insulin and glucose requirements to maintain normoglycemia until the day after surgery. The bedside artificial pancreas achieved intensive glycemic control without hypoglycemia under fasting conditions for 15 h after surgery (mean blood glucose level was 103.3 ± 3.1 mg/dL and percentage of time in range (70—140 mg/dL) was 99.4 ± 2.0%). The total insulin requirement for maintaining normoglycemia differed among surgical procedures, including the use of cardiopulmonary bypass during surgery, while it was not affected by age, body mass index, or the capacity of insulin secretion. Moreover, the mean insulin requirement and the standard deviation of the insulin requirements were variable and high, especially during the first several hours after surgery. Treatment using the bedside artificial pancreas enabled intensive postoperative glycemic control without hypoglycemia. Furthermore, the insulin requirements for maintaining normoglycemia after cardiac surgery vary based on surgical strategies and change dynamically with postoperative time, even in the short term.