Abstract 2314: Insulin is the Protective Component of Glucose-Insulin-Potassium Solutions during Coronary Artery Bypass Graft Surgery in Patients with Diabetes

Abstract

Maintaining glycemic control(120 –180mg/dl)with GIK solutions in patients with diabetes undergoing CABG decreases perioperative morbidity and enhances long-term survival. The mechanism by which GIK exerts its protective effects is unknown. This study was undertaken to determine whether it is substrate enhancement with glucose, glycemic control with insulin, or the combination of glucose + insulin + potassium which contributes to improved outcomes with GIK in CABG patients with diabetes. One hundred-twenty diabetic patients undergoing isolated CABG surgery were prospectively randomized to achieve glycemic control(120 –180mg/dl)using an INSULIN infusion(100units/100mlNS),LOW GIK(500mlD5W + 80units insulin + 40mEqKCL), and HIGH GIK(D20W + 200units insulin + 80mEqKCL) beginning on anesthetic induction and continuing for 18 hours after surgery. Variables assessed included Major Adverse Events(MAE=death, MI, CVA, atrial fibrillation, infection, ventilation > 24 hours, inotropic usage > 24hours,lenght of stay > 7days), serum glucose, the amount of insulin infused, and serum free fatty acids(ffa).Values are mean+/− standard deviation. HIGH GIK delivered more insulin and resulted in significantly lower levels of glucose and ffa. However, it had no effect on the incidence of MAEs compared to INSULIN infusions without glucose and potassium. Insulin, rather than substrate enhancement with glucose and potassium, is the key element in GIK used in CABG patients with diabetes. Augmenting insulin delivery results in lower levels of glucose and ffa, but has no effect on clinical outcomes as long as gylcemic control(120 –180mg/dl) is achieved. This research has received full or partial funding support from the American Heart Association, AHA National Center. RESULTS