A Novel Noninvasive Blood Glucose Monitor

Abstract

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 ϭ 32 mg/dl, mean absolute relative error (%MARE) ϭ 11.6, with a correlation coefficient of r ϭ 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 ϭ 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. Diabetes Care 25:2268 -2275, 2002T here are a number of reviews (1,2) on approaches for noninvasive blood glucose (BG) measurements. In recent years, infrared (IR) spectroscopy has emerged as the analytical method of choice, founded on the spectrum of IR colors characteristic of the analyte itself instead of relying on reagents and color reactions. Different approaches in IR absorption are described in several published studies (3-10).The advanced prototype presented here is based on thermal emission spectroscopy (TES) (11-18) and promises a new generation of noninvasive human tissue analyte instruments. This methodology is fundamentally different from previous attempts at using near-IR techniques (1). The method and instrument are based on the discovery that natural mid-IR emission from the human body, especially from the tympanic membrane, is modulated by the state of the emitting tissue. Spectral emissivity of human IR radiation from the tympanic membrane consists of spectral information of the blood analyte. This can be directly correlated with the blood analyte concentration (for example, the glucose concentration). Tympanic membrane thermometers, currently widely used at home and in the hospit...

Glucose sensors: a review of current and emerging technology

“…Good correlation was found ( r = 0.87) and 100% of points were in areas A and B of the Clarke error grid [34].…”

Multivariate calibration of NIR spectroscopic sensors for continuous glucose monitoring

“…Optical techniques, such as polarimetry [25], Raman spectroscopy [26], diffuse reflection spectroscopy [27,28], absorption spectroscopy [28,29], thermal emission spectroscopy [30,31], fluorescence spectroscopy [32] and photoacoustic (PA) spectroscopy [33,34], have been investigated to monitor levels of glucose in blood continuously in a non-invasive way. Several papers have reviewed different technologies in detail [35][36][37].…”

Accuracy of a Novel Noninvasive Multisensor Technology to Estimate Glucose in Diabetic Subjects During Dynamic Conditions

“…This is not a trivial issue since other noninvasive experimental sensors have been shown to be negatively affected by motion artifact and body temperature. 12,25 We found that even in those dynamic conditions the SWA estimations performed fairly well. However, the correlation coefficient and MARDs were noted to be better during TTs than the OGTTs, suggesting that the performance of both devices is less optimal during rapid plasma glucose excursions.…”