The literature suggests that appropriate glycemic control in the ICU reduces morbidity and overall mortality in the critically ill. [1,2,3] Nonetheless, the difficulties in establishing a working glycemic control policy in the ICU are challenging. Typically, clinicians’ fear of inducing hypoglycemia is the first obstacle to overcome in launching an improvement effort. Doctors remain wary of inducing hypoglycemia and may not have confidence in selecting appropriate doses. Nurses fear hypoglycemia and remain concerned about protocolized adjustments to intravenous insulin rates of administration. The balance of evidence suggests, however, that once these barriers are addressed, ICU patients receive better care with appropriate glycemic control.
Insulin, Glucose Co-Administration:
Studies supporting the role of glycemic control have variably used continuous infusion of insulin along with glucose or enteral nutrition as a feeding source. The methods used in the foundational study by Van den Berghe and colleagues employed a continuous infusion of glucose or enteral nutrition in all subjects. Insulin was infused concomitantly to maintain glucose between 80 and 110 mg/dL (4.4–6.1 mmol/L). [1] However, the NICE-SUGAR study left nutritional management to the discretion of treating clinicians in the individual ICUs of the 42 hospitals participating in the trial. These investigators reported that during the first 14 days after randomization, the mean daily amount of nonprotein calories administered was 891±490 kcal in the intensive-control group and 872±500 kcal in the conventional-control group (P = 0.14). [3] In the Van den Berghe trials, exogenous glucose was begun simultaneously with insulin, with frequent monitoring of glucose (every 1 hour) and intensity of monitoring was greatest at the time of initiation of insulin. [1,2] Given the variation in feeding protocols, it is unclear what the optimal feeding recommendation is during administration of intravenous insulin to maintain glucose control. However, the NICE-SUGAR study again allowed for the type of variation that might typically be seen in everyday use across hospitals.
Protocols and Frequency of Monitoring Serum Glucose:
Details of the NICE-SUGAR protocols are available at https://studies.thegeorgeinstitute.org/nice/. Control of blood glucose was achieved with the use of an intravenous infusion of insulin in saline. In the group of patients assigned to undergo conventional glucose control, insulin was administered if the blood glucose level exceeded 180 mg per deciliter; insulin administration was reduced and then discontinued if the blood glucose level dropped below 144 mg per deciliter (8.0 mmol per liter). Blood glucose levels in each patient were managed as part of the normal duties of the clinical staff at the participating center. In the Van den Berghe protocol, glucose levels were monitored frequently after initiation of the protocol (every 30 to 60 minutes) and on a regular basis (every 4 hours) once the blood glucose concentration had stabilized. This protocol was provided by the investigators as an appendix to their study and can be found on the website of the New England Journal of Medicine.
Watch for Hypoglycemia:
We recommend clinicians pay particular attention to glycemic control to prevent metabolic complications and to ensure adequate nutritional support. Hypoglycemia may occur when controlling glucose values in critically ill patients. In the NICE-SUGAR study, severe hypoglycemia (defined as a blood glucose level ≤40 mg per deciliter [2.2 mmol per liter]) was recorded in 206 of 3,016 patients (6.8 percent) undergoing intensive glucose control, as compared with 15 of 3,014 patients (0.5 percent) undergoing conventional control (odds ratio, 14.7; 95 percent CI, 9.0 to 25.9; P<0.001). The recorded number of episodes of severe hypoglycemia was 272 in the intensive-control group, as compared with 16 in the conventional-control group. [3]
Compliance with your organization’s protocol may be better if appropriate safety controls are built into your management strategy. Adequate staff education and a written, explicit protocol are prerequisites to beginning your work on glucose control and may help to prevent episodes of hypoglycemia.
Nutritional Support:
A strategy of glycemic control should include efforts to provide adequate nutrition with the preferential use of the enteral route. A strategy of apprpriate glycemic control should be carefully coordinated with particular patients’ level of nutritional support and metabolic status, which changes frequently in critically ill patients.
Clinical Evidence:
- Van den Berghe G, Wouters P, Weekers F, et al. Intensive insulin therapy in critically ill patients. New England Journal of Medicine. 2001 Nov 8;345(19):1359-1367.
- Van den Berghe G, Wilmer A, Hermans G, et al. Intensive insulin therapy in the medical ICU. New England Journal of Medicine. 2006 Feb 2;354(5):449-461.
- NICE-SUGAR Study Investigators, Finfer S, Chittock DR, Su SY, et al. Intensive versus conventional glucose control in critically ill patients. New England Journal Medicine. 2009 Mar 26;360(13):1283-1297.
