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Multicenter Study
. 2015 Nov;17(11):787-94.
doi: 10.1089/dia.2014.0378. Epub 2015 Jul 14.

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

Timothy Bailey  1 , Bruce W Bode  2 , Mark P Christiansen  3 , Leslie J Klaff  4 , Shridhara Alva  5
Affiliations
Multicenter Study

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

Timothy Bailey et al. Diabetes Technol Ther. 2015 Nov.

Abstract

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.

Trial registration: ClinicalTrials.gov NCT02073058.

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Figures

<b>FIG. 1.</b>
FIG. 1.
(Left panel) Consensus and (right panel) Clarke Error Grid Analysis comparing the FreeStyle Libre sensor readings with capillary blood glucose reference values using the FreeStyle Precision meter built into the Reader.
<b>FIG. 2.</b>
FIG. 2.
Histogram of the mean absolute relative difference (MARD) per sensor.
<b>FIG. 3.</b>
FIG. 3.
Stability of accuracy across 14 days of Freestyle Libre sensor wear: Consensus Error Grid Zone A (green), Zone B (blue), and Zone C (red). N is the number of paired sensor and reference data points per day of wear for all sensors used in the study.
<b>FIG. 4.</b>
FIG. 4.
Accuracy of the FreeStyle Libre sensor as a function of various factors or patient characteristics: (A) diabetes type, (B) sex, (C) insertion site, (D) insulin administration (Insulin Ad) (continuous subcutaneous insulin infusion [CSII] or multiple daily insulin injections [MDI]), (E) body mass index (BMI), (F) hemoglobin A1c (HbA1c), (G) age, and (H) rate of change. Consensus Error Grid zones were Zone A (green), Zone B (blue), and Zone C (red).
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