A Novel Noninvasive Blood Glucose Monitor
- 1University of Connecticut Health Center, School of Medicine, Division of Endocrinology and Metabolism, Farmington, Connecticut
- 2Infratec, Inc., Wilton, Connecticut
OBJECTIVE—To evaluate the precision and accuracy of a new advanced prototype of a noninvasive blood glucose monitor across a wide range of serum glucose concentrations.
RESEARCH DESIGN AND METHODS—An advanced handheld noninvasive glucose monitor prototype was calibrated and tested using patients recruited by the General Research Center of the University of Connecticut Health Center. The monitor, developed by Infratec, uses principles of thermal emission spectroscopy. The noninvasive measurement of tympanic membrane glucose concentration was calibrated to the serum glucose concentration using 432 paired measurements from 20 subjects with insulin-requiring diabetes. This calibration was subsequently tested (results of power analyses) in a blind fashion with 126 paired measurements from six diabetic subjects who require insulin.
RESULTS—In vivo measurements demonstrated the reproducibility of the methodology of the noninvasive glucose monitor. Based on the calibration model, predicted glucose concentrations for six subjects were as follows (for 126 data points): SD = 32 mg/dl, mean absolute relative error (%MARE) = 11.6, with a correlation coefficient of r = 0.87. Noninvasive glucose results were also compared with laboratory reference measurements using an error-in-variables method. Clark error grid analysis showed that 100% of the measurements fell within zones A and B (90% in zone A and 10% in zone B). The SD for all noninvasive measured concentrations was 27 mg/dl, %MARE was 8.6, and the correlation coefficient was r = 0.94.
CONCLUSIONS—This first independent clinical study of an advanced noninvasive blood glucose prototype based on thermal emission in the mid-infrared spectral region has demonstrated glucose measurements with clinically acceptable accuracy but without the necessity of individual daily calibration.
- %MARE, mean absolute relative error
- BG, blood glucose
- IR, infrared
- TES, thermal emission spectroscopy
Address correspondence and reprint requests to Dr. Janusz M. Buchert, Infratec, Inc., 539 Danbury Rd., Wilton, CT 06897. E-mail:.
Received for publication 7 February 2002 and accepted in revised form 16 August 2002.
C.M. and K.S. are paid consultants for Infratec, Inc.; J.L. is CEO and a member of the Board of Directors of Infratec, Inc.; and J.M.B. is Founder, President, and a member of the Board of Directors of and holds stock in Infratec, Inc.
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
- DIABETES CARE