ABSTRACT
Laboratory for Optical Sensing and Monitoring, Center for Biomedical Engineeer-
ing, Department of Neuroscience and Cell Biology, and Department of Anesthesiol-
ogy, The University of Texas Medical Branch, Galveston, TX 77555-0456, USA
Donald S. Prough
Department of Anesthesiology, The University of Texas Medical Branch, Galveston,
TX 77555-0591, USA
18.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564
18.2 Noninvasive Optical Techniques for Glucose Monitoring . . . . . . . . . . . . . . . . . . 566
18.3 Optical Coherence Tomography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567
18.4 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
18.5 Studies in Tissue Phantoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 570
18.6 Animal Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
18.7 Specificity Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572
18.8 Clinical Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 574
18.9 Mechanisms of Glucose-Induced Changes in Optical Properties of Tissue . . 576
18.10 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 579
Monitoring and control of blood glucose concentration substantially minimize com-
plications, mortality, and morbidity associated with diabetes. We have developed a
high-resolution optical technique, Optical Coherence Tomography (OCT), for non-
invasive, continuous, accurate monitoring of blood glucose concentration. OCT is
based on detection of backscattered low-coherent light and utilizes scattering con-
trast in tissues. It has a resolution of 1-15 µm and a probing depth of about 1 mm. In this chapter we review major achievements in the development of this technique for
noninvasive glucose monitoring from the concept phase to successful clinical stud-
ies. Our initial phantom, animal, and clinical tests on glucose monitoring with this
technique demonstrated that the OCT signal slope is linearly dependent on glucose
of
concentration. Initial in vivo studies in animals and volunteers revealed good corre-
lation of the OCT signal slope with blood glucose concentration. Then we modified
the hardware, software, and signal acquisition and processing algorithms and per-
formed another set of animal and clinical studies. The modified system allows for
robust measurement of OCT signal slope with high accuracy and resolution from
specific tissue layers. The results obtained with the modified system demonstrated
substantially higher correlation of the OCT signal slope with blood glucose concen-
tration and minimal (a few minutes) lag time between them. Moreover, our in vivo
studies with the modified system revealed reproducibility, accuracy, and specificity
approaching that of standard invasive techniques. The obtained results demonstrate
that the proposed technique may be used for noninvasive, continuous, accurate mon-
itoring of blood glucose concentration.
