Accuracy of the Third Generation of a 14-Day Continuous Glucose Monitoring System.

INTRODUCTION: We have evaluated the performance of the FreeStyle Libre® 3 continuous glucose monitoring system (FSL3) compared to (1) the venous plasma reference for participants aged ≥ 6 years and (2) the fingerstick capillary blood glucose (BG) reference for pediatric participants aged 4 and 5 years. The analytical performance of the third-generation factory-calibrated FSL3 CGM system was compared to the plasma venous blood glucose reference using the YSI 2300 STAT PLUS Glucose and Lactate Analyzer (the YSI reference) and the self-monitoring blood glucose (SMBG) reference for participants aged ≥ 6 years and participants aged 4 and 5 years, respectively. METHODS: A total of 108 participants aged ≥ 4 years with type 1 or type 2 diabetes from four sites in the USA were enrolled in the study. The data of 100 participants were ultimately evaluated. Adult participants (aged ≥ 18 years) participated in three in-clinic sessions, and pediatric participants (aged 4-17 years) participated in up to two in-clinic sessions, all stratified to provide data for days 1, 2, 3, 7, 8, 9, 12, 13 or 14 of sensor wear. Performance evaluation included accuracy measures, such as proportion of CGM values that fell within ± 20% or ± 20 mg/dL (1.1 mmol/L) of the reference glucose values, and difference measures, such as the mean absolute relative difference (MARD) between the CGM and reference values. RESULTS: Data from the 100 study participants were analyzed. The overall MARD was 7.8%, and 93.4% of the CGM values were within ± 20% or ± 20 mg/dL of the YSI reference for participants aged ≥ 6 years, with 6845 CGM-YSI matched pairs. The performance was stable over the 14-day wear period. For participants aged 4-5 years, MARD was 10.0%, and 88.9% of the CGM values were within 20%/20 mg/dL compared to a SMBG reference. No serious adverse events were reported. CONCLUSIONS: The FSL3 CGM system demonstrated accurate performance across the dynamic glycemic range during the 14-day sensor wear period.

Accuracy of a 14-Day Factory-Calibrated Continuous Glucose Monitoring System With Advanced Algorithm in Pediatric and Adult Population With Diabetes.

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.

Landscape of Continuous Glucose Monitoring (CGM) and Integrated CGM: Accuracy Considerations.

Continuous glucose monitoring devices have significantly improved in many respects compared with earlier versions. As sensor accuracy improved, U.S. Food and Drug Administration approved a nonadjunctive indication for use that no longer required confirmatory blood glucose monitoring. This article discusses the performance characteristics and regulatory classifications for the current systems that are relevant to informed clinical decision-making.

Feasibility of Continuous Ketone Monitoring in Subcutaneous Tissue Using a Ketone Sensor.

BACKGROUND: The feasibility of measuring ß-hydroxybutyrate in ISF using a continuous ketone monitoring (CKM) sensor using a single calibration without further adjustments over 14 days is described. METHODS: A CKM sensor was developed using wired enzyme technology with ß-hydroxybutyrate dehydrogenase chemistry. In vitro characterization of the sensor was performed in phosphate buffered saline at 37°C. In vivo performance was evaluated in 12 healthy participants on low carbohydrate diets, who wore 3 ketone sensors on the back of their upper arms to continuously measure ketone levels over 14 days. Reference capillary ketone measurements were performed using Precision Xtra® test strips at least 8 times a day. RESULTS: The sensor is stable over 14 days and has a linear response over the 0-8 mM range. The operational stability of the sensor is very good with a 2.1% signal change over 14 days. The first human study of the CKM sensor demonstrated that the sensor can continuously track ketones well through the entire 14 days of wear. The performance with a single retrospective calibration of the sensor showed 82.4% of data pairs within 0.225 mM/20% and 91.4% within 0.3 mM/30% of the capillary ketone reference (presented as mM at <1.5 mM and as percentage at or above 1.5 mM). This suggests that the sensor can be used with a single calibration for the 14 days of use. CONCLUSIONS: Measuring ketones in ISF using a continuous ketone sensor is feasible. Additional studies are required to evaluate the performance in intended patient populations, including conditions of ketosis and diabetic ketoacidosis.

The YSI 2300 Analyzer Replacement Meeting Report.

This is a summary report of the most important aspects discussed during the YSI 2300 Analyzer Replacement Meeting. The aim is to provide the interested reader with an overview of the complex topic and propose solutions for the current issue. This solution should not only be adequate for the United States or Europe markets but also for all other countries. The meeting addendum presents three outcomes of the meeting.

The Performance and Usability of a Factory-Calibrated Flash Glucose Monitoring System.

INTRODUCTION: The purpose of the study was to evaluate the performance and usability of the FreeStyle(®) Libre™ Flash glucose monitoring system (Abbott Diabetes Care, Alameda, CA) for interstitial glucose results compared with capillary blood glucose results. MATERIALS AND METHODS: Seventy-two study participants with type 1 or type 2 diabetes were enrolled by four U.S. clinical sites. A sensor was inserted on the back of each upper arm for up to 14 days. Three factory-only calibrated sensor lots were used in the study. Sensor glucose measurements were compared with capillary blood glucose (BG) results (approximately eight per day) obtained using the BG meter built into the reader (BG reference) and with the YSI analyzer (Yellow Springs Instrument, Yellow Springs, OH) reference tests at three clinic visits (32 samples per visit). Sensor readings were masked to the participants. RESULTS: The accuracy of the results was demonstrated against capillary BG reference values, with 86.7% of sensor results within Consensus Error Grid Zone A. The percentage of readings within Consensus Error Grid Zone A on Days 2, 7, and 14 was 88.4%, 89.2%, and 85.2%, respectively. The overall mean absolute relative difference was 11.4%. The mean lag time between sensor and YSI reference values was 4.5±4.8 min. Sensor accuracy was not affected by factors such as body mass index, age, type of diabetes, clinical site, insulin administration, or hemoglobin A1c. CONCLUSIONS: Interstitial glucose measurements with the FreeStyle Libre system were found to be accurate compared with capillary BG reference values, with accuracy remaining stable over 14 days of wear and unaffected by patient characteristics.

Clinical evaluation of the FreeStyle Precision Pro system.

BACKGROUND: A new version of international standard (ISO 15197) and CLSI Guideline (POCT12) with more stringent accuracy criteria are near publication. We evaluated the glucose test performance of the FreeStyle Precision Pro system, a new blood glucose monitoring system (BGMS) designed to enhance accuracy for point-of-care testing (POCT). METHODS: Precision, interference and system accuracy with 503 blood samples from capillary, venous and arterial sources were evaluated in a multicenter study. Study results were analyzed and presented in accordance with the specifications and recommendations of the final draft ISO 15197 and the new POCT12. RESULTS: The FreeStyle Precision Pro system demonstrated acceptable precision (CV <5%), no interference across a hematocrit range of 15-65%, and, except for xylose, no interference from 24 of 25 potentially interfering substances. It also met all accuracy criteria specified in the final draft ISO 15197 and POCT12, with 97.3-98.9% of the individual results of various blood sample types agreeing within ±12 mg/dl of the laboratory analyzer values at glucose concentrations <100mg/dl and within ±12.5% of the laboratory analyzer values at glucose concentrations ≥100 mg/dl. CONCLUSIONS: The FreeStyle Precision Pro system met the tighter accuracy requirements, providing a means for enhancing accuracy for point-of-care blood glucose monitoring.

Performance of a glucose meter with a built-in automated bolus calculator versus manual bolus calculation in insulin-using subjects.

BACKGROUND: Patients consider multiple parameters in adjusting prandial insulin doses for optimal glycemic control. Difficulties in calculations can lead to incorrect doses or induce patients to administer fixed doses, rely on empirical estimates, or skip boluses. METHOD: A multicenter study was conducted with 205 diabetes subjects who were on multiple daily injections of rapid/ short-acting insulin. Using the formula provided, the subjects manually calculated two prandial insulin doses based on one high and one normal glucose test result, respectively. They also determined the two doses using the FreeStyle InsuLinx Blood Glucose Monitoring System, which has a built-in, automated bolus calculator. After dose determinations, the subjects completed opinion surveys. RESULTS: Of the 409 insulin doses manually calculated by the subjects, 256 (63%) were incorrect. Only 23 (6%) of the same 409 dose determinations were incorrect using the meter, and these errors were due to either confirmed or potential deviations from the study instructions by the subjects when determining dose with meter. In the survey, 83% of the subjects expressed more confidence in the meter-calculated doses than the manually calculated doses. Furthermore, 87% of the subjects preferred to use the meter than manual calculation to determine prandial insulin doses. CONCLUSIONS: Insulin-using patients made errors in more than half of the manually calculated insulin doses. Use of the automated bolus calculator in the FreeStyle InsuLinx meter minimized errors in dose determination. The patients also expressed confidence and preference for using the meter. This may increase adherence and help optimize the use of mealtime insulin.

Performance of a new test strip for freestyle blood glucose monitoring systems.

BACKGROUND: a new strip, designed to enhance the ease of use and minimize interference of non-glucose sugars, has been developed to replace the current FreeStyle (Abbott Diabetes Care, Alameda, CA) blood glucose test strip. We evaluated the performance of this new strip. METHODS: laboratory evaluation included precision, linearity, dynamic range, effects of operating temperature, humidity, altitude, hematocrit, interferents, and blood reapplication. System accuracy, lay user performance, and ease of use for finger capillary blood testing and accuracy for venous blood testing were evaluated at clinics. Lay users also compared the speed and ease of use between the new strip and the current FreeStyle strip. RESULTS: for glucose concentrations <75 mg/dL, 73%, 100%, and 100% of the individual capillary blood glucose results obtained by lay users fell within ± 5, 10, and 15 mg/dL, respectively, of the reference. For glucose concentrations ≥75 mg/dL, 68%, 95%, 99%, and 99% of the lay user results fell within ± 5%, 10%, 15%, and 20%, respectively, of the reference. Comparable accuracy was obtained in the venous blood study. Lay users found the new test strip easy to use and faster and easier to use than the current FreeStyle strip. The new strip maintained accuracy under various challenging conditions, including high concentrations of various interferents, sample reapplication up to 60 s, and extremes in hematocrit, altitude, and operating temperature and humidity. CONCLUSIONS: our results demonstrated excellent accuracy of the new FreeStyle test strip and validated the improvements in minimizing interference and enhancing ease of use.

FreeStyle Lite--a blood glucose meter that requires no coding.

BACKGROUND: Abbott Diabetes Care introduced the FreeStyle Lite blood glucose monitoring system, which simplifies the management of diabetes. The FreeStyle Lite system relies on FreeStyle technology but eliminates the need for coding the meter for individual strip lots. The meter is precoded for the FreeStyle Lite strips. FreeStyle systems use coulometry technology where the glucose signal is calculated from the total charge generated as a result of the glucose reaction in the sample. FreeStyle strip calibration parameters can be controlled by controlling the sample volume. Coulometry technology is less sensitive to measurement conditions such as temperature and hematocrit. FreeStyle chemistry is less sensitive to interference from electroactive compounds. The ability to control calibration parameters coupled to a robust measurement technology enabled the development of a blood glucose monitoring system that does not require coding by the user. METHODS: Laboratory studies were performed to determine analytical performance, such as linearity, precision, and sensitivity to operating temperature. Clinical accuracy for finger tip capillary blood testing was assessed with five lots of FreeStyle Lite test strips. FreeStyle Lite results in these studies were compared to the plasma equivalent glucose values of finger tip blood samples measured by the Yellow Springs Instrument glucose analyzer. RESULTS: In the analytical performance evaluation, repeatability (within-run precision) of the FreeStyle Lite system showed an average standard deviation of 3.4 mg/dl (0.19 mmol/liter) at glucose concentrations <100 mg/dl (<5.56 mmol/liter) and an average coefficient of variation of 4.3% at glucose concentrations > or =100 mg/dl (> or =5.56 mmol/liter). Linearity demonstrated across the measuring range of the FreeStyle Lite system was 20-500 mg/dl (1.1-27.8 mmol/liter) with r(2) > 0.99. The FreeStyle Lite system was also shown to maintain accuracy across the operating temperature range of 4 to 40 degrees C. CONCLUSIONS: The FreeStyle Lite system has good analytical performance and clinical accuracy. While simplifying the process of blood glucose monitoring, the FreeStyle Lite system continues to provide the performance that users have come to expect from FreeStyle products.