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. 2014 Jan;8(1):89-94.
doi: 10.1177/1932296813511747. Epub 2014 Jan 1.

Feasibility of Factory Calibration for Subcutaneous Glucose Sensors in Subjects With Diabetes

Udo Hoss  1 , Erwin S Budiman  2 , Hanqing Liu  2 , Mark P Christiansen  3
Affiliations

Feasibility of Factory Calibration for Subcutaneous Glucose Sensors in Subjects With Diabetes

Udo Hoss et al. J Diabetes Sci Technol. 2014 Jan.

Abstract

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.

Keywords: calibration; continuous glucose monitoring; diabetes; glucose sensor; subcutaneous.

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Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Hoss, Budiman, and Liu are employees of Abbott Diabetes Care. Christiansen is an employee of Diablo Clinical Research, Walnut Creek, CA.

Figures

Figure 1.
Figure 1.
In vitro sensitivity of sensors tested under ambient conditions at 37°C. Least square regression results in an average slope of 0.96 nA/mM and a coefficient of variation between sensors of 2.9% (n = 49). Error bars represent the SD of the measurements.
Figure 2.
Figure 2.
In vivo sensitivity values (paired sensor/reference values) based on capillary blood glucose plotted against elapsed time since sensor start. Lowermost and uppermost lines correspond to the 10th and 90th percentiles. Middle bands correspond to the lower quartile, median, and upper quartile lines. Regression line shows a sensor drift over time of 0.66%/day.
Figure 3.
Figure 3.
(a) Per sensor in vivo sensitivity with error bars representing the per subject standard error (SE). The coefficient of variation for in vivo sensitivity for all sensors was 6.0%, and the difference between subjects was not statistically significant (P = .069). (b) Box plot of sensor in vivo sensitivity by insertion site. There was no statistically significant difference in sensitivity between abdomen and arm sites (P = .104).
Figure 4.
Figure 4.
Consensus error grid analysis of sensor glucose values using a single calibration factor to simulate sensor factory calibration (n = 5445).
See this image and copyright information in PMC

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References

    1. Liebl A, Henrichs HR, Heinemann L, et al. Continuous glucose monitoring: evidence and consensus statement for clinical use. J Diabetes Sci Technol. 2013;7(2):500-519. - PMC - PubMed
    1. Wisniewski N, Moussy F, Reichert WM. Characterization of implantable biosensor membrane biofouling. Fresenius J Anal Chem. 2000;366(6-7):611-621. - PubMed
    1. Hoss U, Jeddi I, Schulz M, et al. Continuous glucose monitoring in subcutaneous tissue using factory-calibrated sensors: a pilot study. Diabetes Technol Ther. 2010;12(8):591-597. - PubMed
    1. Feldman B, Brazg R, Schwartz S, et al. A continuous glucose sensor based on Wired Enzyme™ technology—results from a 3-day trial in patients with type 1 diabetes. Diabetes Technol Ther. 2003;5(5):769-782. - PubMed
    1. McGarraugh G, Brazg R, Weinstein R. FreeStyle Navigator Continuous Glucose Monitoring System with TRUstart Algorithm, a 1-hour warm-up time. J Diabetes Sci Technol. 2011;5(1):99-106. - PMC - PubMed