Characterizing Accuracy and Precision of Glucose Sensors and Meters

• Published in: Journal of diabetes science and technology Vol. 8; no. 5; pp. 980 - 985
• Main Author: Rodbard, David
• Format: Journal Article
• Language: English
• Published: Los Angeles, CA SAGE Publications 01-09-2014
• Subjects: Blood Glucose - analysis; Blood Glucose Self-Monitoring - standards; Humans; Models, Statistical; Monitoring, Physiologic - standards; Original; Parkes error grid; precision; accuracy; Bland–Altman plot; glucose monitoring; self-monitoring of blood glucose; mean absolute relative deviation (MARD); Clarke error grid; bias; precision absolute relative deviation (PARD); diabetes mellitus type 2; continuous glucose monitoring; statistical analysis; diabetes mellitus type 1
• ISSN: 1932-2968; 1932-2968; 1932-3107
• DOI: 10.1177/1932296814541810

Background:
There is need for a method to describe precision and accuracy of glucose measurement as a smooth continuous function of glucose level rather than as a step function for a few discrete ranges of glucose. We propose and illustrate a method to generate a “Glucose Precision Profile” showing absolute relative deviation (ARD) and /or %CV versus glucose level to better characterize measurement errors at any glucose level.
Method:
We examine the relationship between glucose measured by test and comparator methods using linear regression. We examine bias by plotting deviation = (test – comparator method) versus glucose level. We compute the deviation, absolute deviation (AD), ARD, and standard deviation (SD) for each data pair. We utilize curve smoothing procedures to minimize the effects of random sampling variability to facilitate identification and display of the underlying relationships between ARD or %CV and glucose level.
Results:
AD, ARD, SD, and %CV display smooth continuous relationships versus glucose level. Estimates of MARD and %CV are subject to relatively large errors in the hypoglycemic range due in part to a markedly nonlinear relationship with glucose level and in part to the limited number of observations in the hypoglycemic range.
Conclusions:
The curvilinear relationships of ARD and %CV versus glucose level are helpful when characterizing and comparing the precision and accuracy of glucose sensors and meters.