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. 2017 Aug;19(8):446-456.
doi: 10.1089/dia.2017.0087. Epub 2017 Jul 12.

Accuracy of a Fourth-Generation Subcutaneous Continuous Glucose Sensor

Mark P Christiansen  1 , Satish K Garg  2 , Ronald Brazg  3 , Bruce W Bode  4 , Timothy S Bailey  5 , Robert H Slover  2 , Ashley Sullivan  6 , Suiying Huang  6 , John Shin  6 , Scott W Lee  6 , Francine R Kaufman  6
Affiliations

Accuracy of a Fourth-Generation Subcutaneous Continuous Glucose Sensor

Mark P Christiansen et al. Diabetes Technol Ther. 2017 Aug.

Abstract

Background: This study evaluated the accuracy and performance of a fourth-generation subcutaneous glucose sensor (Guardian™ Sensor 3) in the abdomen and arm.

Methods: Eighty-eight subjects (14-75 years of age, mean ± standard deviation [SD] of 42.0 ± 19.1 years) with type 1 or type 2 diabetes participated in the study. Subjects wore two sensors in the abdomen that were paired with either a MiniMed™ 640G insulin pump, or an iPhone® or iPod® touch® running a glucose monitoring mobile application (Guardian Connect system) and a third sensor in the arm, which was connected to a glucose sensor recorder (GSR). Subjects were also asked to undergo in-clinic visits of 12-14 h on study days 1, 3, and 7 for frequent blood glucose sample testing using a Yellow Springs Instrument (YSI) reference.

Results: The overall mean absolute relative difference (MARD ± SD) between abdomen sensor glucose (SG) and YSI reference values was 9.6% ± 9.0% and 9.4% ± 9.8% for the MiniMed 640G insulin pump and Guardian Connect system, respectively; and 8.7% ± 8.0% between arm SG and YSI reference values. The percentage of SG values within 20% agreement of the YSI reference value (for YSI >80 mg/dL) was 90.7% with the MiniMed 640G insulin pump, 91.8% with the Guardian Connect system, and 93.1% for GSR-connected arm sensors. Mean functional sensor life, when calibrating 3-4 times/day, was 145.9 ± 39.3 h for sensors paired with the MiniMed 640G insulin pump, 146.1 ± 41.6 h for sensors paired with the Guardian Connect system, and 147.6 ± 40.4 h for sensors connected to the GSR. Responses to survey questions regarding sensor comfort and ease of use were favorable.

Conclusions: The Guardian Sensor 3 glucose sensor, whether located in abdomen or the arm, provided accurate glucose readings when compared with the YSI reference and demonstrated functional life commensurate with the intended 7-day use. ClinicalTrials.gov : NCT02246582.

Keywords: Glucose sensor; MARD; Mobile device; Sensor accuracy; Sensor-integrated pump.

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Conflict of interest statement

The study's principal investigators: Drs. Christiansen, Garg, Brazg, Bode, Bailey, and Slover received research support and compensation for conducting the study from Medtronic. Francine R. Kaufman, MD; Scott W. Lee, MD; John Shin, PhD, MBA; Suiying Huang, MSc; Ashley Sullivan, MSc; and Toni L. Cordero, PhD, employees of Medtronic, were involved in the data analysis, development, and/or critical review of the article. The study was funded by Medtronic.

Figures

<b>FIG. 1.</b>
FIG. 1.
Study flow and subject disposition.
<b>FIG. 2.</b>
FIG. 2.
Guardian Sensor 3 sensor.
<b>FIG. 3.</b>
FIG. 3.
Distributions of overall ARD by device. The percentage of sensor glucose-YSI paired points associated with ranges (0% to >40%) of the overall ARD, according to each device, are shown when calibrating every 12 h (Top) and 3–4 times each day (Bottom). The percent distribution of values when calibrating every 12 h and 3–4 times each day are listed in Table 3. Black: MiniMed 640G insulin pump, Gray: Guardian Connect system, White: Glucose Sensor Recorder. ARD, absolute relative difference; YSI, Yellow Springs Instrument.
<b>FIG. 4.</b>
FIG. 4.
Overall ARD, as a function of YSI reference values, by device. The percent ARD distributions relative to YSI reference values (mg/dL) are shown, by device, when calibrating every 12 h (Top) and 3–4 times each day (Bottom). The horizontal line across each graph indicates the mean. GSR, glucose sensor recorder.
See this image and copyright information in PMC

Comment in

  • Advances in Subcutaneous Glucose Sensing.
    Castle JR. Castle JR. Diabetes Technol Ther. 2017 Aug;19(8):441-442. doi: 10.1089/dia.2017.0233. Epub 2017 Aug 2. Diabetes Technol Ther. 2017. PMID: 28767273 Free PMC article. No abstract available.

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