Continuous insulin infusion reduces mortality in patients with diabetes undergoing coronary artery bypass grafting.
OBJECTIVE
Diabetes mellitus is a risk factor for death after coronary artery bypass grafting. Its relative risk may be related to the level of perioperative hyperglycemia. We hypothesized that strict glucose control with a continuous insulin infusion in the perioperative period would reduce hospital mortality.


METHODS
All patients with diabetes undergoing coronary artery bypass grafting (n = 3554) were treated aggressively with either subcutaneous insulin (1987-1991) or with continuous insulin infusion (1992-2001) for hyperglycemia. Predicted and observed hospital mortalities were compared with both internal and external (Society of Thoracic Surgeons 1996) multivariable risk models.


RESULTS
Observed mortality with continuous insulin infusion (2.5%, n = 65/2612) was significantly lower than with subcutaneous insulin (5.3%, n = 50/942, P <.0001). Likewise, glucose control was significantly better with continuous insulin infusion (177 +/- 30 mg/dL vs 213 +/- 41 mg/dL, P <.0001). For internal comparison, multivariable analysis showed that continuous insulin infusion was independently protective against death (odds ratio 0.43, P =.001). Conversely, cardiogenic shock, renal failure, reoperation, nonelective operative status, older age, concomitant peripheral or cerebral vascular disease, decreasing ejection fraction, unstable angina, and history of atrial fibrillation increased the risk of death. For external comparison, observed mortality with continuous insulin infusion was significantly less than that predicted by the model (observed/expected ratio 0.63, P <.001). Multivariable analysis revealed that continuous insulin infusion added an independently protective effect against death (odds ratio 0.50, P =.005) to the constellation of risk factors in the Society of Thoracic Surgeons risk model.


CONCLUSIONS
Continuous insulin infusion eliminates the incremental increase in in-hospital mortality after coronary artery bypass grafting associated with diabetes. The protective effect of continuous insulin infusion may stem from the effective metabolic use of excess glucose to favorably alter pathways of myocardial adenosine triphosphate production. Continuous insulin infusion should become the standard of care for glycometabolic control in patients with diabetes undergoing coronary artery bypass grafting.
Furnary
Anthony P
AP
Department of Cardiothoracic Surgery, Providence St Vincent Medical Center, Oregon Health and Science University, Portland, OR 97225, USA. tfurnary@starrwood.com
Gao
Guangqiang
G
Grunkemeier
Gary L
GL
Wu
YingXing
Y
Zerr
Kathryn J
KJ
Bookin
Stephen O
SO
Floten
H Storm
HS
Starr
Albert
A
D000368:Aged; D001786:Blood Glucose; D001026:Coronary Artery Bypass / Q000401:mortality*; D003327:Coronary Disease / Q000150:complications / Q000401:mortality / Q000601:surgery*; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000401:mortality; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage / Q000627:therapeutic use*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011446:Prospective Studies
D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin