Accuracy of the Dexcom G6 Continuous Glucose Monitoring System Following Cardiac Surgery

Study Overview
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Brief Summary
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This is a prospective longitudinal study to study the agreement between a novel continuous glucose monitoring system (CGMS) versus current blood glucose monitoring. Subjects in this study will have their blood glucose measured regularly every 1-3 hours with current methods in the cardiovascular intensive care unit (CVICU), and by point of care glucose using the Accuchek Inform II on the regular floors, and the CGMS at the same time will be captured. Subjects will have measurements taken throughout their stay in the CVICU and on the regular floors.

Detailed Description
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Maintaining tight blood glucose control following surgery is imperative to reducing infections and neurologic dysfunction. This requires frequent blood sampling while in the intensive care unit, leading to increased waste of blood and utilizing time and resources to collect samples and wait for results. Additionally, when on the regular floors, frequent point of care fingersticks for glucose levels are needed for therapeutic intervention. Continuous glucose monitoring systems (CGMS) are now available for ambulatory use in patients with diabetes. The potential of using such a system in the hospital, including during the postoperative critical care setting and upon transfer to the regular floor, may reduce personnel burden, produce rapid results, and decrease blood waste. However, these systems have not yet been validated for hospital use. This is a prospective longitudinal study to study the agreement between a novel continuous glucose monitoring system (CGMS) versus current blood glucose monitoring. Subjects in this study will have their blood glucose measured regularly every 1-3 hours with current methods in the CVICU, and by point of care glucose using the Accuchek Inform II on the regular floors, and the CGMS at the same time will be captured. Subjects will have measurements taken throughout their stay in the CVICU and on the regular floors. Agreement and correlation between systems will be calculated, and error will be classified using the Surveillance Error grid. The proportion of errors of at least moderate risk will be calculated. Subject characteristics including demographics, comorbidities and baseline disease severity will be summarized using means and standard deviations for continuous measures and frequencies and percentages for categorical factors. To evaluate agreement between methods, concordance correlation coefficients will be calculated, using the method that adjusts for repeated measures as described by King and implemented in software by Carrasco. Analysis will be performed overall, and then stratifying by type of current measure, if the type of measurement varies across settings. Correlations will be calculated using the methods described by Bland and Altman and implemented by Bakdash and Marusich. Differences will also be evaluated for errors according to the Surveillance Error Grid. Rates of moderate or more severe errors will be calculated. For each measure above, 95% confidence intervals will be calculated, accounting for the clustering within subject.. Analyses will be performed using SAS software (version 9.4; Cary, NC) and R software (version 3.5; Vienna Austria). Glucose readings obtained from the CGMS will be compared with blood glucose from the arterial blood gas (ABG) or peripheral/central venous catheter if arterial catheter not in use (standard of care in CVICU) while patients are in the CVICU fingerstick point of care (POC) glucose when patients are on the regular floors

Official Title
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Accuracy of the Dexcom G6 Continuous Glucose Monitoring System Following Cardiac Surgery

Conditions
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Surgery--Complications

Intervention / Treatment
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* Device: Dexcom G6 continuous glucose monitor


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18 years and above Planned cardiovascular surgery Planned admission to Cleveland Clinic Main Campus J5 or J6 or Q5 cardiovascular ICU (CVICU) post-operatively With or without known diabetes; if with known diagnosis of diabetes, diabetes can be type 1, type 2, or secondary Exclusion Criteria: Allergy to the material of the CGMS or the adhesive to be used Skin conditions precluding the use of the CGMS Pregnancy Other conditions that investigators deem inappropriate for the study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Supportive Care
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Dexcom G6 continuous glucose monitor<br>All patients will have a Dexcom G6 continuous glucose monitor placed pre-operatively. The glucose readings will be collected for 10 days or upon discharge from the ICU and data will be compared with arterial blood glucose readings or venous Accu-Check Inform II glucose readings | Device: Dexcom G6 continuous glucose monitor<br>* Dexcom G6 continuous glucose monitor will be applied to the upper outer arm before cardiovascular surgery. Data will be collected for 10 days or upon discharge from the ICU.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Glucose readings from CGM versus from blood | Glucose readings in mg/dL from the Dexcom CGMS will be compared with blood glucose in mg/dL from the arterial blood gas (ABG) or peripheral/central venous catheter | Up to 10 days | 
| Glucose readings from CGM versus point of care glucose | Glucose readings in mg/dL from the Dexcom CGMS will be compared with fingerstick point of care glucose levels in mg/dL | up to 10 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Cost comparison of Dexcom CGMS versus blood glucose testing | The cost of the Dexcom CGMS device including the sensor and transmitter will be compared to the cost of measuring glucose from arterial blood gas | Up to 10 days | 
| Cost comparison of Dexcom CGMS versus fingerstick point of care glucose | The cost in US$ of the Dexcom CGMS device including the sensor and transmitter will be compared to the cost in US$ of measuring glucose from point of care fingerstick testing (Accuchek Inform II meter, test strips, and lancets) | Up to 10 days |