Accuracy and reliability of a subcutaneous continuous glucose-monitoring system in critically ill patients

BACKGROUND:Continuous glucose monitoring has been proposed to optimize glucose control in critically ill patients. To achieve strict glucose regulation, accurate and reliable continuous glucose-monitoring systems are essential. OBJECTIVE:Evaluation of a subcutaneous continuous glucose-monitoring system for use in critically ill patients. DESIGN:Pooled-data analysis of two prospective, randomized, controlled trials. SETTING:An eight-bed medical intensive care unit of a university hospital. PATIENTS:A total of 174 critically ill patients on intensive insulin therapy. INTERVENTIONS:Subcutaneous continuous glucose monitoring. MEASUREMENTS:Two thousand forty-five continuous glucose-monitoring system sensor glucose values were compared with arterial reference blood glucose levels, determined by a blood gas analyzer. Continuous glucose monitoring data were recorded continuously for up to 72 hrs by using a subcutaneous continuous glucose-monitoring sensor. The correlation of both methods and differences between continuous glucose-monitoring systems and reference values were calculated, as well as the conformity of continuous glucose-monitoring values with the International Organization for Standardization criteria (75 mg/dL]). RESULTS:The Pearson correlation coefficient was 0.92, showing strong correlation between the two methods. The intraclass correlation coefficient was 0.92, indicating that 92% of the variability is due to subjects and measurement occasions. Mean difference between continuous glucose-monitoring system and reference values was −0.10 mmol/L (confidence interval−0.13 to −0.07) (−2 mg/dL [confidence interval−2 to −1]) (continuous glucose-monitoring system minus reference) and absolute difference 0.44 mmol/L (confidence interval0.41–0.47) (8 mg/dL [confidence interval7–8]). According to the insulin titration error grid analysis, 99.1% of continuous glucose-monitoring system values were in the acceptable treatment zone. No continuous glucose-monitoring system measurements were found in the life-threatening zone, and 92.9% of the continuous glucose-monitoring system glucose values met the International Organization for Standardization criteria. CONCLUSION:The subcutaneous continuous glucose-monitoring system is reliable for use in critically ill patients and showed glucose values with a strong correlation to arterial re