Accuracy of Glucose Trends by Subcutaneous Continuous Monitoring vs Intermittent Arterial Measurements in Critically...

Continuous glucose monitoring (CGM) has the potential to improve glucose control in critically ill patients, provided that its trend accuracy is reliable. We evaluated the trend accuracy of a subcutaneous CGM system (Dexcom G6) compared with intermittent arterial blood gas (ABG) measurements in intensive care unit (ICU) patients receiving insulin.

We enrolled 40 adult ICU patients receiving insulin and organ-supportive therapies. We assessed trend accuracy using the Rate Error Grid Analysis (R-EGA) and the Diabetes Technology Society Trend Accuracy Matrix (DTS-TAM), overall, across different ABG levels, and over time from CGM initiation.

A total of 2701 paired CGM-ABG trends were analyzed, with a median (IQR) time difference between readings of 83 (65-125) minutes. Overall, 99.7% of trends were classified in R-EGA Zone A and 0.3% in Zone B. On DTS-TAM analysis, 98.6% of trends fell in the No Risk category, while 1.7% were in the adjacent Mild-to-Moderate Risk categories. Trends were more frequently categorized as Mild-to-Moderate Risk when ABG values were <100 mg/dL (5.56 mmol/L) (3.6%) compared with 100 to 180 mg/dL (5.56 to 10 mmol/L) (1.3%) or >180 mg/dL (10 mmol/L) (1.6%). During the first 24 hours of CGM use, 2.9% of trends fell into the Mild-to-Moderate Risk categories, compared with 0.9% beyond 24 hours.

In critically ill patients receiving insulin, CGM demonstrated high overall trend accuracy relative to ABG. Trend accuracy was reduced at lower glucose ranges and during the initial 24 hours of CGM use.