Intensive Intraoperative Insulin Therapy Versus Conventional Glucose Management During Cardiac Surgery: a Randomized Trial

Background: It is not known whether rigorous intraoperative glycemic control reduces death and morbidity in cardiac surgery patients.

Objective: To compare outcomes of intensive insulin therapy during cardiac surgery with those of conventional intraoperative glucose management.

Design: A randomized, open-label, controlled trial with blinded end point assessment.

Setting: Tertiary care center.

Patients: Adults with and without diabetes who were undergoing on-pump cardiac surgery.

Measurements: The primary outcome was a composite of death, sternal infections, prolonged ventilation, cardiac arrhythmias, stroke, and renal failure within 30 days after surgery. Secondary outcome measures were length of stay in the intensive care unit and hospital.

Intervention: Patients were randomly assigned to receive continuous insulin infusion to maintain intraoperative glucose levels between 4.4 (80 mg/dL) and 5.6 mmol/L (100 mg/dL) (n = 199) or conventional treatment (n = 201). Patients in the conventional treatment group were not given insulin during surgery unless glucose levels were greater than 11.1 mmol/L (>200 mg/dL). Both groups were treated with insulin infusion to maintain normoglycemia after surgery.

Results: Mean glucose concentrations were statistically significantly lower in the intensive treatment group at the end of surgery (6.3 mmol/L [SD, 1.6] [114 mg/dL {SD, 29}] in the intensive treatment group vs. 8.7 mmol/L [SD, 2.3] [157 mg/dL {SD, 42}] in the conventional treatment group; difference, -2.4 mmol/L [95% CI, -2.8 to -1.9 mmol/L] [-43 mg/dL {CI, -50 to -35 mg/dL}]). Eighty two of 185 patients (44%) in the intensive treatment group and 86 of 186 patients (46%) in the conventional treatment group had an event (risk ratio, 1.0 [CI, 0.8 to 1.2]). More deaths (4 deaths vs. 0 deaths; P = 0.061) and strokes (8 strokes vs. 1 strokes; P = 0.020) occurred in the intensive treatment group. Length of stay in the intensive care unit (mean, 2 days [SD, 2] vs. 2 days [SD, 3]; difference, 0 days [CI, -1 to 1 days]) and in the hospital (mean, 8 days [SD, 4] vs. 8 days [SD, 5]; difference, 0 days [CI, -1 to 0 days]) was similar for both groups.

Limitations: This single-center study used a composite end point and could not examine whether outcomes differed by diabetes status.

Conclusions: Intensive insulin therapy during cardiac surgery does not reduce perioperative death or morbidity. The increased incidence of death and stroke in the intensive treatment group raises concern about routine implementation of this intervention.