San Francisco Injury Center (SFIC) »  Full Research Descriptions »  Glucose Control in the ICU at San Francisco General Hospital

Investigatation of Glucose Control in the Intensive Care Unit (ICU) via Strict Versus Moderate Insulin Infusion protocol

Project Director/Lead Investigator: Mitchell Cohen, MD

Brief Summary of Project: A recent paper published in the New England Journal of Medicine reported that tight glucose control in a heterogeneous group of ICU patients resulted in greater morbidity and mortality. (The NICE-SUGAR Study Investigators. Intensive versus Conventional Glucose Control in Critically Ill Patients. NEJM. 2009;360:13-1283-97). Unfortunately, no data exists on the glucose control parameters maintained by our ICU patient protocol, the rate of hyper or hypoglycemia, or the outcome in a primarily surgical population. This retrospective trial will examine the level and effectiveness of glucose control protocols currently applied to our severely injured and ill ICU population at SFGH.

Specific Aims:
1. To determine the range of glucose control achieved in our surgical/trauma ICU population. (Status: In progress)
2. To determine the rate of hyperglycemic and hypoglycemic events in our surgical/trauma ICU population. (Status: In progress)
3. To determine the effect of glucose levels and insulin protocol on outcome in our surgical/trauma ICU population. (Status: In progress)
4. To implement an evidence-based recommendation of insulin infusion protocol for acutely injured patients that optimizes outcome.

Studies and Results: We retrospectively reviewed 1422 trauma patients with at least 3-day ICU
stay and 5 glucose measurements from May 2001 - January 2010, spanning three nonoverlapping,
sequential glucose control protocols: 'relaxed', 'aggressive', and 'moderate'. For each, we extracted mean blood glucose, hypoglycemic and hyperglycemic event frequency, and glucose variability, and investigated their association with outcomes. Mortality was associated with elevated mean glucose (135.6 vs. 126.2 mg/dL), more frequent hypoglycemic (2.67 ± 7 vs. 1.28 ± 5) and hyperglycemic (30.6 ± 28 vs. 16.0 ± 22 per 100 patient-ICU-days) events, and higher glucose variability (37.1 ± 20 vs. 29.4 ± 20; all p < 0.001). Regression identified hyperglycemic episodes (p < 0.05) as an independent predictor of mortality. The 'moderate' regimen had rare hyperglycemia, low glucose variability, and intermediate mean blood glucose range and frequency of hypoglycemia. Multiorgan failure and mortality did not differ between groups. Hyperglycemic events (glucose > 180 mg/dL) most strongly predicted mortality. Of glucose control protocols analyzed, the 'moderate' protocol had fewest hyperglycemic events. As outcomes were otherwise equivalent between 'moderate' and 'aggressive' protocols, we conclude that hyperglycemia can be safely avoided using a moderate glycemic control protocol without inducing hypoglycemia.

Significance: The correct balance of glycemic control is understudied in the critically-injured trauma population. These patients tend to be younger and have lower pre-existing incidence of diabetes compared to the patient populations in previous trials consisting of a mixed surgical and medical/surgical populations, and frequently face unique challenges such as multiple operative interventions and attendant changes in enteral and intravenous nutrition schedules that can cause rapid fluctuations in blood glucose. Given conflicting data regarding optimal glycemic control in critically-injured trauma patients, we sought to describe previous and current existing glycemic control regimens at our institution in terms of relevant glycemic control parameters, and to evaluate their relative efficacy and outcomes. This retrospective review of our institutional experience spanning three distinct glycemic control regimens, identified hyperglycemia as a significant predictor of mortality in critically-injured trauma patients. Of the three protocols assessed, the 'moderate' glycemic control regimen most optimally balances maintenance of normoglycemia, reduction in glucose variability, and minimization of hypo- and hyperglycemic events, while maintaining equivalent outcomes when compared to a more aggressive strategy.