Intensive Insulin Therapy Has No Effect on Mortality and Morbidity in Cardiac Surgery Patients: A Meta-Analysis

Abstract

Introduction: Optimal glycemic control in cardiac surgery patients remains a laudable but confusing practice. Existing studies have primarily employed two maintenance strategies using either intensive insulin therapy (IIT) (maintain glucose < 120 mg/dl) or conventional insulin therapy (CIT) (<200 mg/dl) with conflicting outcomes. This meta-analysis evaluates the impact of IIT and CIT in regards to the incidence of mortality, length of stay (LOS), intensive care unit (ICU) LOS, atrial fibrillation (AF), and infections. Methods: A comprehensive literature search in PubMed, Google Scholar and the Cochrane Central Registry of Controlled Trials was completed between 1966 and 2016. Keywords searched were “insulin”, “bypass”, “coronary”, “CABG”, “glucose”, “artery”, “intensive”, “cardiac”, and “surgery”. Eligible studies were randomized control trials (RCTs) comparing IIT (BGL 80-120 mg/dL) and CIT (BGL < 200 mg/dL). Primary outcomes were mortality, ICU LOS, and hospital LOS. Results: 8 RCTs were included in this study. IIT strategies did not significantly affect overall mortality (RR = 0.905, 95% CI = 0.604 to 1.356; p = 0.628), ICU LOS (MD = -0.073 days, 95% CI = -0.324 to 0.178; p = 0.568), or hospital LOS (MD = 0.269, 95% CI = -2.158 to 2.696; p = 0.828). No difference in AF rates (RR = 0.887, 95% CI = 0.681 to 1.155; p = 0.375) or deep sternal infection (RR = 0.985, 95% CI = 0.357 to 2.720; p = 0.977) were observed. Conclusion: IIT targeting blood sugar levels of 80 - 120 mg/dl have no effect on perioperative outcomes in cardiac surgery patients. IIT is associated with similar mortality, ICU LOS, hospital LOS, AF rates, and deep sternal infection rates compared to more liberal glycemic strategies. IIT should not replace CIT as the standard of care in cardiac surgery patients.