A New-Generation Continuous Glucose Monitoring System: Improved Accuracy and Reliability Compared with a Previous-Generation System

Self Cite

149

119

Background : We assessed the performance of a modified Dexcom G4 Platinum system with an advanced algorithm, in comparison with frequent venous samples measured on a laboratory reference (YSI) during a clinic session and in comparison to self-monitored blood glucose (SMBG) during home use. Methods:Fifty-one subjects with diabetes were enrolled in a prospective multicenter study. Subjects wore 1 sensor for 7-day use and participated in one 12-hour in-clinic session on day 1, 4, or 7 to collect YSI reference venous glucose every 15 minutes and capillary SMBG test every 30 minutes. Carbohydrate consumption and insulin dosing and timing were manipulated to obtain data in low and high glucose ranges. Results:In comparison with the laboratory reference method (n = 2,263) the system provided a mean and median absolute relative differences (ARD) of 9.0% and 7.0%, respectively. The mean absolute difference for CGM was 6.4 mg/dL when the YSIs were within hypoglycemia ranges (≤ 70 mg/dL). The percentage in the clinically accurate Clarke error grid A zone was 92.4% and in the benign error B zone was 7.1%. Majority of the sensors (73%) had an aggregated MARD in reference to YSI ≤ 10%. The MARD of CGM-SMBG for home use was 11.3%. Conclusions:The study showed that the point and rate accuracy, clinical accuracy, reliability, and consistency over the duration of wear and across glycemic ranges were superior to current commercial real-time CGM systems. The performance of this CGM is reaching that of a self-monitoring blood glucose meter in real use environment.

Section: Original Articlementioning

confidence: 71%

Clinical Accuracy of a Continuous Glucose Monitoring System With an Advanced Algorithm

Bailey

Chang

Christiansen

2014

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149

119

“…21 We did not notice any large sensor overreading with the current sensor. We could only find 1 previous publication assessing the accuracy of the Dexcom G4 Platinum sensor showing an aggregate mean ARD of 13% 22 and 1 conference abstract with a mean ARD of 10.8%. 23 The Dexcom sensor was used in anterior abdominal wall, which is an approved location, and this study was not designed to assess sensor performance based on location.…”

Section: Discussionmentioning

confidence: 90%

Evaluating the Performance of a Novel Embedded Closed-loop System

Leelarathna

Thabit

Allen

et al. 2014

Despite significant improvements in the care of type 1 diabetes, achieving tight glycemic control while avoiding hypoglycemia 1,2 remains a challenge for many patients and novel therapeutic approaches are required. Closed-loop insulin delivery is an emerging treatment option for patients with type 1 diabetes. 3 Compared to preprogrammed basal insulin rates in insulin pumps, closed-loop insulin delivery systems modulate insulin delivery in glucose-responsive fashion based on subcutaneous sensor glucose levels utilizing advanced computer algorithms. 3Several studies have evaluated the safety and efficacy of closed-loop under laboratory conditions and shown promising results. These include evaluations using a randomized design by our group in youths, 4,5 adults, 6 and pregnant women 7 and by others using the model predictive control algorithm, 8,9 , the proportional-integral-derivative approach, 10,11 and the fuzzy logic controller. 12,13 Insulin and glucagon coadministration have also been applied in randomized studies.14-16 Several of above studies [4][5][6][7] were conducted in the manual operational mode where sensor glucose values were entered into a laptop computer running the algorithm followed by manual adjustment of the insulin pump. More recently automated closed-loop control systems utilizing an ultra-portable laptop computer 17 or mobile phone platform 18 have also been described. In February 2010, the European Union granted funding for the AP@home project (Artificial Pancreas at Home), a consortium of European academic medical centers, biotechnology companies, and industrial partners, to carry out closed-loop glucose control research. 19 The ultimate goal of the AP@home project is to develop a closed-loop system for use outside clinical research centers. The primary objective of the current study was to evaluate the reliability of the first , on behalf of the AP@home consortium AbstractThe objective was to assess the reliability of a novel automated closed-loop glucose control system developed within the AP@home consortium in adults with type 1 diabetes. Eight adults with type 1 diabetes on insulin pump therapy (3 men; ages 40.5 ± 14.3 years; HbA1c 8.2 ± 0.8%) participated in an open-label, single-center, single-arm, 12-hour overnight study performed at the clinical research facility. A standardized evening meal (80 g CHO) accompanied by prandial insulin boluses were given at 19:00 followed by an optional snack of 15 g at 22:00 without insulin bolus. Automated closed-loop glucose control was started at 19:00 and continued until 07:00 the next day. Basal insulin delivery (Accu-Chek Spirit, Roche) was automatically adjusted by Cambridge model predictive control algorithm, running on a purpose-built embedded device, based on real-time continuous glucose monitor readings (Dexcom G4 Platinum). Closed-loop system was operational as intended over 99% of the time. Overnight plasma glucose levels (22:00 to 07:00) were within the target range (3.9 to 8.0 mmol/l) for 75.4% (37.5, 92.9) of the time without any ti...

“…Christiansen and coauthors 10 have published a comparative analysis of the performance of the new G4 PLATINUM and the previous SEVEN PLUS CGM systems. 12 The percentage of CGM readings in the clinically accurate Clarke error grid A zone increased from 74% for the SEVEN PLUS to 80% for the G4 PLATINUM. The mean absolute relative difference (MARD) decreased from 15.9% ± 8.6% for the SEVEN PLUS to 13.2% ± 6.7% for the G4 PLATINUM.…”

Section: Introductionmentioning

confidence: 95%

Dexcom G4AP: An Advanced Continuous Glucose Monitor for the Artificial Pancreas

García

Rack-Gomer

Bhavaraju

et al. 2013

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Input from continuous glucose monitors (CGMs) is a critical component of artificial pancreas (AP) systems, but CGM performance issues continue to limit progress in AP research. While G4 PLATINUM has been integrated into AP systems around the world and used in many successful AP controller feasibility studies, this system was designed to address the needs of ambulatory CGM users as an adjunctive use system. Dexcom and the University of Padova have developed an advanced CGM, called G4AP, to specifically address the heightened performance requirements for future AP studies. The G4AP employs the same sensor and transmitter as the G4 PLATINUM but contains updated denoising and calibration algorithms for improved accuracy and reliability. These algorithms were applied to raw data from an existing G4 PLATINUM clinical study using a simulated prospective procedure. The results show that mean absolute relative difference (MARD) compared with venous plasma glucose was improved from 13.2% with the G4 PLATINUM to 11.7% with the G4AP. Accuracy improvements were seen over all days of sensor wear and across the plasma glucose range (40-400 mg/dl). The greatest improvements occurred in the low glucose range (40-80 mg/dl), in euglycemia (80-120 mg/dl), and on the first day of sensor use. The percentage of sensors with a MARD <15% increased from 69% to 80%. Metrics proposed by the AP research community for addressing specific AP requirements were also computed. The G4AP consistently exhibited improved sensor performance compared with the G4 PLATINUM. These improvements are expected to enable further advances in AP research.