The use of commercially available continuous glucose monitors for diabetes management requires sensor calibrations, which until recently are exclusively performed by the patient. A new development is the implementation of factory calibration for subcutaneous glucose sensors, which eliminates the need for user calibrations and the associated blood glucose tests. Factory calibration means that the calibration process is part of the sensor manufacturing process and performed under controlled laboratory conditions. The ability to move from a user calibration to factory calibration is based on several technical requirements related to sensor stability and the robustness of the sensor manufacturing process. The main advantages of factory calibration over the conventional user calibration are: (a) more convenience for the user, since no more fingersticks are required for calibration and (b) elimination of use errors related to the execution of the calibration process, which can lead to sensor inaccuracies. The FreeStyle Libre TM and FreeStyle Libre Pro TM flash continuous glucose monitoring systems are the first commercially available sensor systems using factory-calibrated sensors. For these sensor systems, no user calibrations are required throughout the sensor wear duration.
The incidence of severe and significant hypoglycemia reduced 2300- and 200-fold, respectively, during stimulated overnight closed loop with MPC compared to that observed during open-loop overnight clinical studies in young subjects with T1DM. Hyperglycemia was 200 times less likely. Overnight closed loop with the FSN and the MPC algorithm is expected to reduce substantially the risk of hypoglycemia and hyperglycemia.
Background: In this study, we evaluated the analytical performance of the second-generation factory-calibrated FreeStyle Libre Flash Glucose Monitoring (FreeStyle Libre 2) System compared to plasma venous blood glucose reference, Yellow Springs Instrument 2300 (YSI). Methods: The study enrolled participants aged four and above with type 1 or type 2 diabetes at seven sites in the United States. Adult participants (18+ years) participated in three in-clinic sessions and pediatric participants (4-17 years) participated in up to two in-clinic sessions stratified to provide data for days 1, 2, 3, 7, 8, 9, 12, 13, or 14 of sensor wear. Participants aged 11+ underwent supervised glycemic manipulation during in-clinic sessions to achieve glucose levels across the measurement range of the System. Performance evaluation included accuracy measures such as the proportion of continuous glucose monitoring (CGM) values that were within ±20% or ±20 mg/dL of reference glucose values, and bias measures such as the mean absolute relative difference (MARD) between CGM and reference values. Results: Data from the 144 adults and 129 pediatric participants were analyzed. Percent of sensor results within ±20%/20 mg/dL of YSI reference were 93.2% and 92.1%, and MARD was 9.2% and 9.7% for the adults and pediatric participants, respectively. The System performed well in the hypoglycemic range, with 94.3% of the results for the adult population and 96.1% of the data for pediatric population being within 15 mg/dL of the YSI reference. The time lag was 2.4 ± 4.6 minutes for adults and 2.1 ± 5.0 minutes for pediatrics. Conclusions: The System demonstrated improved analytical accuracy performance across the dynamic range during the 14-day sensor wear period as compared to the previous-generation device. NCT#: NCT03607448 and NCT03820050
The study shows that a 14-day sensor wear period is achievable. Moreover, sensors using "wired enzyme" technology showed excellent in vivo stability, with no significant sensitivity loss over the 14-day wear period.
Background: Continuous glucose monitoring using subcutaneously inserted sensors currently requires blood glucose tests for sensor calibration. Alternatively, sensors precalibrated during the manufacturing process may eliminate the need for fingerstick calibrations. In this study we evaluated the feasibility of sensor factory calibration in subjects with diabetes. Methods: A total of 33 subjects with diabetes were asked to wear 4 sensors in parallel, 2 on the arm and 2 on the abdomen. Sensors from a lot with low in vitro sensitivity coefficient of variation were used in the study. Based on frequent capillary blood glucose measurements, the average glucose sensitivity of each sensor was determined over a 5-day wear time. The in vivo sensitivities were analyzed for inter-and intrasubject variation. Mean absolute relative difference (MARD) calculation and consensus error grid analysis (EGA) were performed using a single calibration factor for all sensors, to simulate factory calibration and compared against conventional finger-stick calibration. Results: The sensitivity coefficient of variation between sensors increased from 2.9% in vitro to 6.0% in vivo. No difference in sensor response between subjects (P = .069) as well as between insertion sites (arm and abdomen) was detected (P = .104). Applying one calibration factor to all sensors in the study resulted in an MARD of 13.4%, and 83.5% of the values fell in consensus EGA zone A. Multiple fingerstick calibration resulted in an MARD of 12.7% and 84.1% in zone A. Conclusions: Feasibility of factory calibration was demonstrated in subjects with diabetes using sensors based on "wired enzyme" technology, resulting in accuracy metrics similar to sensors calibrated with capillary blood glucose.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.