Glucose control in the intensive care unit

Abstract

Objective: Hyperglycemia, be it secondary to diabetes, impaired glucose tolerance, impaired fasting glucose, or stress-induced is common in the critically ill. Hyperglycemia and glucose variability in intensive care unit (ICU) patients has some experts calling for routine administration of intensive insulin therapy to normalize glucose levels in hyperglycemic patients. Others, however, have raised concerns over the optimal glucose level, the accuracy of measurements, the resources required to attain tight glycemic control (TGC), and the impact of TGC across the heterogeneous ICU population in patients with diabetes, previously undiagnosed diabetes or stress-induced hyperglycemia. Increased variability in glucose levels during critical illness and the therapeutic intervention thereof have recently been reported to have a deleterious impact on survival, particularly in nondiabetic hyperglycemic patients. The incidence of hypoglycemia (<40 mg/dL or 2.2 mmol) associated with TGC is reported to be as high as 18.7%, by Van den Berghe in a medical ICU, although application of various approaches and computer-based algorithms may improve this. The impact of hypoglycemia, particularly in patients with septic shock and those with neurologic compromise, warrants further evaluation. This review briefly discusses the epidemiology of hyperglycemia in the acutely ill and glucose metabolism in the critically ill. It comments on present limitations in glucose monitoring, outlines current glucose management approaches in the critically ill, and the transition from the ICU to the intermediate care unit or ward. It closes with comment on future developments in glycemic care of the critically ill.

Methods: The awareness of the potential deleterious impact of hyperglycemia was heightened after Van den Berghe et al presented their prospective trial in 2001. Therefore, source data were obtained from PubMed and Cochrane Analysis searches of the medical literature, with emphasis on the time period after 2000. Recent meta-analyses were reviewed, expert editorial opinion collated, and the Web site of the Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation Trial investigated.

Summary and conclusions: Hyperglycemia develops commonly in the critically ill and impacts outcome in patients with diabetes but, even more so, in patients with stress-induced hyperglycemia. Despite calls for TGC by various experts and regulatory agencies, supporting data remain somewhat incomplete and conflicting. A recently completed large international study, Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation, should provide information to further guide best practice. This concise review interprets the current state of adult glycemic management guidelines to provide a template for care as new information becomes available.