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.

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.