Factors in Accuracy Studies Influencing Measured CGM Performance.

Study Overview
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Brief Summary
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Primary objective is to assess the impact of different reference glucose measurement methods on the measured performance of a CGM system, aiming at further standardization for the assessment of CGM systems. Secondary objective is to describe the relationship between glucose concentration of venous, capillary and arterialized-venous measurement samples. Study design: Open-label trial. Study population: Nineteen patients with type 1 diabetes aged 18 years and older will be included. Intervention: The study will use the Dexcom G5 Mobile CGM. The participant will visit the clinical research center (CRC) twice during a 6 day period. These visits will have a duration of 8 hours. Blood will be drawn for the determination of glucose concentrations using venous, arterialized-venous and capillary sampling techniques. The patient will receive his usual breakfast and an increased insulin bolus will be administered to correct the breakfast glucose excursion with the aim of inducing a period of minor hypoglycemia. Blood sampling will continue until the end of the admission. The sensor will be worn until the end of the second 8-hour CRC session, which will be planned on day 6 or earlier depending on patient preference. The sensor will be removed and their sensor and blood glucose meter data downloaded from the devices. In the case of sensor failure before the first CRC session, patients will be instructed to insert a new sensor per the manufacturer's instruction and to notify study staff of the event. In case of failure of the sensor after the first CRC session but before the second CRC session, patients will return to the CRC for sensor removal and for data download.

Official Title
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Factors in Accuracy Studies Influencing Measured CGM Performance: a Comparison of Measured Continuous Glucose Monitor Performance Using Venous, Arterialized-venous and Capillary Reference Glucose Samples.

Conditions
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Diabetes Mellitus, Type 1

Intervention / Treatment
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* Device: Arterialized-venous reference (YSI)
* Device: Venous reference measurement (YSI)
* Device: Capillary reference (SMBG)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: diagnosed with type 1 DM at least 6 months according to the WHO definition Body Mass Index (BMI) <35 kg/m² willing and able to wear a CGM device for the duration of the study and undergo all study procedures HbA1c <10% Signed informed consent form prior to study entry Exclusion Criteria: patient is pregnant, or breast feeding during the period of the study. patient is using a medication that significantly impacts glucose metabolism (oral steroids) except if stable for at least the last three months and expected to remain stable for the study duration. patient requires regular use of acetaminophen (paracetamol) while participating in the study due to known negative impact on CGM performance. patient is actively enrolled in another clinical trial or took part in a study within 30 days. known adrenal gland problem, panhypopitutarism, gastroparesis, migraine, epilepsy or ischemic heart disease or other cardiovascular event in the year previous to study participation . inability of the patient to comply with all study procedures. inability of the patient to understand the patient information. patient donated blood in the last 3 months. has severe medical or psychological condition(s) or chronic conditions/infections that in the opinion of the investigator would compromise the patient's safety or successful participation in the study. is assessed by the investigators to have difficult intravenous (IV) access .

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: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Arterialized-venous reference YSI<br>CGM monitoring performance per arterialized venous reference measurement (YSI) | Device: Arterialized-venous reference (YSI)<br>* All patients will be fitted with the a CGM system, Dexcom G5 Mobile, patients receive an iv-catheter to sample venous blood. The samples will be arterialized using a heated-hand-box (arterialized-venous reference (YSI). Blood will be drawn for the determination of glucose concentrations using arterialized-venous sampling techniques per YSI.<br>|
| Experimental: Venous reference samples YSI<br>CGM monitoring performance per venous reference measurement (YSI) | Device: Venous reference measurement (YSI)<br>* All patients will be fitted with the a CGM system, Dexcom G5 Mobile, patients receive an iv-catheter to sample venous blood. Blood will be drawn for the determination of glucose concentrations using venous sampling techniques measured per YSI.<br>Device: Capillary reference (SMBG)<br>* All patients will be fitted with the a CGM system, Dexcom G5 Mobile, patients receive vingerstick measurements to sample capillary blood measured per Self Monitoring of Blood Glucose (SMBG) device.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean Absolute Relative Difference (MARD) | MARD will be assessed per average of the 8 hour arterialization and regular venous study visit. | up to day 6 of use | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Accuracy of sensors (MARD) per hypoglycemic range | Accuracy of the sensor in the hypoglycaemic (defined as a blood glucose value ≤70 mg/dL) area as an average of the first six days of use. | up to day 6 of use | 
| Accuracy (MARD) of sensors per hyperglycemic range | Accuracy of the sensor in the hyperglycaemic (defined as a blood glucose value >180 mg/dL) area as an average of the first six days of use. | up to day 6 of use | 
| Glucose content (mg/dL) of venous reference samples. | Glucose content of venous reference samples will be measured per YSI. | Up day 6 of study during both intervention visits | 
| Glucose content (mg/dL) of venous-arterialized reference samples. | Glucose content of venous-arterialized reference samples will be measured per YSI. | up day 6 of study during both intervention visits | 
| Glucose content (mg/dL) of capillary reference samples. | Glucose content of capillary reference samples will be measured per SMBG. | up day 6 of study during both intervention visits |