The Performance of Dexcom G6 Glucose Monitoring in Critically Ill Patients

The Performance of Dexcom G6 Glucose Monitoring in Critically Ill Patients

This is an investigator-initiated, prospective, observational accuracy-study. The aim of the study is to test the feasibility, safety, and accuracy of a subcutaneous continuous glucose monitoring system (the Dexcom G6 glucose monitoring system) in critically ill patients. A total of 40 adult patients admitted to the intensive care unit requiring intravenous insulin infusion to maintain blood glucose within target range will be enrolled. Subcutaneous glucose readings will be compared with routine arterial blood glucose measurements to determine accuracy.

The primary endpoint of the study is the mean absolute relative difference (MARD) in percent between CGM and arterial glucose values. Calculations show that 40 patients are required for a 95% confidence interval for the mean to have a range of ±1.7%, meaning that MARD can be estimated with high precision. Calculations of confidence intervals were done using normal approximation, assuming an SD of 5.5 percentage units.

The following variables will be collected from the electronic medical record (Take Care), from the ICU-specific patient data management system (Clinisoft) and/or from the handheld Dexcom G6 monitor:

Patient-related variables:

• Age, sex, height and weight
• Comorbidities (including diabetes status)
• Chronic medications

Clinical variables:

• Date and time of ICU admission and discharge
• Reason for ICU admission
• Admission source (e.g. emergency department, other hospital, ward)
• Illness severity scores (e.g. SAPS [Simplified Acute Physiology Score], SOFA [Sequential Organ Failure Assessment])
• Hemodynamic variables (e.g. heart rate, blood pressure)
• Blood gas results (including blood glucose concentration)
• Other routine laboratory results (e.g. serum creatinine, serum albumin, haematocrit)
• ICU mortality

Treatment variables:

• Insulin doses (including continuous intravenous infusion rates, intravenous and subcutaneous insulin boluses) and times
• Doses and administration time for other medications given in the ICU (e.g. Vasopressors, paracetamol)

Continuous Glucose Monitoring (CGM)-related variables:

• Date and time of sensor insertion
• Sensor insertion site
• Number and duration of disconnection episodes
• Reason for disconnection
• Date and time of sensor calibrations
• Sensor glucose values with date and time stamps
• Date and time of sensor removal
• Reason for sensor removal
• Complications at sensor insertion site (redness, swelling, infection, bruising)

Exact date and time of sensor insertion will be manually recorded in a case report form at the bedside. Every time an arterial blood gas is obtained, the arterial blood glucose value and the corresponding CGM glucose value will be manually recorded along with date and time in the case report form. At the end of the study period, after removing the CGM sensor, CGM-data will be downloaded from the handheld Dexcom G6 monitor.

Inclusion Criteria:

• Age ≥18 years
• Admitted to ICU at the Karolinska University Hospital Solna
• Indwelling arterial catheter in situ or expected to be inserted in the next 2 hours
• Six hours or less since intravenous insulin infusion was commenced or intravenous insulin infusion expected to commence within the next 2 hours
• Vasopressor infusion ongoing or expected to commence within the next 2 hours
• Mechanical ventilation ongoing or expected to commence within the next 2 hours
• Patient expected to stay in the ICU until the day after tomorrow

Exclusion Criteria:

• Pregnancy
• Unable to get consent from patient or next-of-kin
• Patients in whom death is considered imminent (within 24 hours)