Accuracy of the continuous glucose monitoring system in inpatient and outpatient conditions (original) (raw)
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Clinica Chimica Acta, 2012
Background: Patients with diabetes are recommended to self-monitor their blood glucose levels also at home. Accuracy of a hand-held glucometer and a Continuous Glucose Monitoring (CGM) device were comparatively evaluated. Methods: Venous blood samples (for reference laboratory determinations; n = 428) were collected from 18 type 1 patients (35-65 years old), immediately followed by capillary measurement (Bayer ContourLink meter) and CGM readings (Medtronic Paradigm). Results: Laboratory values did not differ statistically from ContourLink and CGM readings, mean difference (±SD) being −0.05 ±1.06 mmol/L and 0.10 ±1.84 mmol/L glucose, respectively. A bias ((value−reference)/reference× 100) ≥15% was observed in 27.7% and 54.9% of cases, respectively. Notably, below 3.9 mmol/L glucose (hypoglycemic threshold), an absolute error>0.8 mmol/L was found in 78.9% and 94.1% of cases. The absolute errors of the CGM device were inversely related to the rate of glucose change (r= 0.598, p b 0.001). Conclusions: A very large error was observed at the extreme glycemic values, which may lead to erroneous therapy. Consequently, performance of future portable glucometers should be focused in particular under hypo-and hyperglycemia. Moreover, integrated CGM devices should not disregard the effect of the rate of blood glucose change on the sensor readings.
Diabetes technology & therapeutics, 2013
Use of continuous glucose monitoring (CGM) systems can improve glycemic control, but widespread adoption of CGM utilization has been limited, in part because of real and perceived problems with accuracy and reliability. This study compared accuracy and performance metrics for a new-generation CGM system with those of a previous-generation device. Subjects were enrolled in a 7-day, open-label, multicenter pivotal study. Sensor readings were compared with venous YSI measurements (blood glucose analyzer from YSI Inc., Yellow Springs, OH) every 15 min (±5 min) during in-clinic visits. The aggregate and individual sensor accuracy and reliability of a new CGM system, the Dexcom(®) (San Diego, CA) G4™ PLATINUM (DG4P), were compared with those of the previous CGM system, the Dexcom SEVEN(®) PLUS (DSP). Both study design and subject characteristics were similar. The aggregate mean absolute relative difference (MARD) for DG4P was 13% compared with 16% for DSP (P<0.0001), and 82% of DG4P re...
Accuracy and Reliability of Current Continuous Glucose Monitoring (CGM) systems; a Direct Comparison
Nederlands Tijdschrift voor Diabetologie, 2012
Objective: This study assessed the accuracy and reliability of three continuous glucose monitoring (CGM) systems. Research Design and Methods: We studied the Animas Ò (West Chester, PA) VibeÔ with Dexcom Ò (San Diego, CA) G4Ô version A sensor (G4A), the Abbott Diabetes Care (Alameda, CA) Freestyle Ò Navigator I (NAV), and the Medtronic (Northridge, CA) Paradigm Ò with EnliteÔ sensor (ENL) in 20 patients with type 1 diabetes mellitus. All systems were investigated both in a clinical research center (CRC) and at home. In the CRC, patients received a meal with a delayed and increased insulin dose to induce a postprandial glucose peak and nadir. Hereafter, randomization determined which two of the three systems would be worn at home until the end of functioning, attempting use beyond manufacturer-specified lifetime. Patients performed at least five reference finger sticks per day. An analysis of variance was performed on all data points ‡ 15 min apart. Results: Overall average mean absolute relative difference (MARD) (SD) measured at the CRC was 16.5% (14.3%) for NAV and 16.4% (15.6%) for ENL, outperforming G4A at 20.5% (18.2%) (P < 0.001). Overall MARD when assessed at home was 14.5% (16.7%) for NAV and 16.5 (18.8%) for G4A, outperforming ENL at 18.9% (23.6%) (P = 0.006). Median time until end of functioning was similar: 10.0 (1.0) days for G4A, 8.0 (3.5) days for NAV, and 8.0 (1.5) days for ENL (P = 0.119). Conclusions: In the CRC, G4A was less accurate than NAV and ENL sensors, which seemed comparable. However, at home, ENL was less accurate than NAV and G4A. Moreover, CGM systems often show sufficient accuracy to be used beyond manufacturer-specified lifetime.
Journal of Diabetes Science and Technology, 2011
Background: This glucose clamp study assessed the performance of an electrochemical continuous glucose monitoring (CGM) system for monitoring levels of interstitial glucose. This novel system does not require use of a trocar or needle for sensor insertion. Method: Continuous glucose monitoring sensors were inserted subcutaneously into the abdominal tissue of 14 adults with type 1 or type 2 diabetes. Subjects underwent an automated glucose clamp procedure with four consecutive post-steady-state glucose plateau periods (40 min each): (a) hypoglycemic (50 mg/dl), (b) hyperglycemic (250 mg/dl), (c) second hypoglycemic (50 mg/dl), and (d) euglycemic (90 mg/dl). Plasma glucose results obtained with YSI glucose analyzers were used for sensor calibration. Accuracy was assessed retrospectively for plateau periods and transition states, when glucose levels were changing rapidly (approximately 2 mg/dl/min). Results: Mean absolute percent difference (APD) was lowest during hypoglycemic plateaus (11.68%, 14.15%) and the euglycemic-to-hypoglycemic transition (14.21%). Mean APD during the hyperglycemic plateau was 17.11%; mean APDs were 18.12% and 19.25% during the hypoglycemic-to-hyperglycemic and hyperglycemic-to-hypoglycemic transitions, respectively. Parkes (consensus) error grid analysis (EGA) and rate EGA of the plateaus and transition periods, respectively, yielded 86.8% and 68.6% accurate results (zone A) and 12.1% and 20.0% benign errors (zone B). Continuous EGA yielded 88.5%, 75.4%, and 79.3% accurate results and 8.3%, 14.3%, and 2.4% benign errors for the euglycemic, hyperglycemic, and hypoglycemic transition periods, respectively. Adverse events were mild and unlikely to be device related. Conclusion: This novel CGM system was safe and accurate across the clinically relevant glucose range.
Manual versus Automated moNitoring Accuracy of GlucosE II (MANAGE II)
Critical Care, 2016
Background: Intravascular continuous glucose monitoring (CGM) may facilitate glycemic control in the intensive care unit (ICU). We compared the accuracy of a CGM device (OptiScanner®) with a standard reference method. Methods: Adult patients who had blood glucose (BG) levels >150 mg/dl and required insertion of an arterial and central venous catheter were included. The OptiScanner® was inserted into a multiple-lumen central venous catheter. Patients were treated using a dynamic-scale insulin algorithm to achieve BG values between 80 and 150 mg/dl. The BG values measured by the OptiScanner® were plotted against BG values measured using a reference analyzer. The correlation between the BG values measured using the two methods and the clinical relevance of any differences were assessed using the coefficient of determination (r 2) and the Clarke error grid, respectively; bias was assessed by the mean absolute relative difference (MARD). Three different standards of glucose monitoring were used to assess accuracy. Glycemic control was assessed using the time in range (TIR). Six indices of glycemic variability were calculated. Results: The analysis included 929 paired samples from 88 patients, monitored for a total of 2584 hours. Reference BG values ranged between 60 and 484 mg/dl. The r 2 value was 0.89. The percentage of BG values within zones A and B of the Clarke error grid was 99.9%; the MARD was 7.7%. Using the ISO 15197 standard and Food and Drug Administration and consensus standards, respectively, 80.4% of measurements were within 15 mg/dl and 88.2% within 15% of reference values, 40% of measurements were within 7 mg/dl and 72.5% within 10% of reference values, and 65.2% of measurements were within 10 mg/dl and 82.7% within 12.5% of reference values. The TIR was slightly lower with the OptiScanner® than with the reference method. The J-index, standard deviation and maximal glucose change were the indices of glycemic variability least affected by the measurement device. Conclusions: Based on the MARD, the performance of the OptiScanner® is adequate for use in ICU patients. Because recent standards for accuracy were not met, the OptiScanner® should not be used as a sole monitor. The assessment of glycemic variability is influenced by the time interval between BG determinations.
Analytical and Clinical Performance of Blood Glucose Monitors
Journal of Diabetes Science and Technology, 2010
The objective of this study was to understand the level of performance of blood glucose monitors as assessed in the published literature. and reference lists of included articles were searched to identify eligible studies. Key information was abstracted from eligible studies: blood glucose meters tested, blood sample, meter operators, setting, sample of people (number, diabetes type, age, sex, and race), duration of diabetes, years using a glucose meter, insulin use, recommendations followed, performance evaluation measures, and specific factors affecting the accuracy evaluation of blood glucose monitors.
Accuracy of the Third Generation of a 14-Day Continuous Glucose Monitoring System
Diabetes Therapy
Introduction: We have evaluated the performance of the FreeStyle LibreÒ 3 continuous glucose monitoring system (FSL3) compared to (1) the venous plasma reference for participants aged C 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 factorycalibrated 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 selfmonitoring blood glucose (SMBG) reference for participants aged C 6 years and participants aged 4 and 5 years, respectively. Methods: A total of 108 participants aged C 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 C 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 C 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.
Diabetes technology & therapeutics, 2013
For self-monitoring of blood glucose by people with diabetes, the reliability of the measured blood glucose values is a prerequisite in order to ensure correct therapeutic decisions. Requirements for system accuracy are defined by the International Organization for Standardization (ISO) in the standard EN ISO 15197:2003. However, even a system with high analytical quality is not a guarantee for accurate and reliable measurement results. Under routine life conditions, blood glucose measurement results are affected by several factors. First, the act of performing measurements as well as the handling of the system may entail numerous possible error sources, such as traces of glucose-containing products on the fingertips, the use of deteriorated test strips, or the incorrect storage of test strips. Second, ambient and sampling conditions such as high altitude, partial pressure of oxygen, ambient temperature, and the use of alternate test sites can have an influence on measurement result...