Continuous noninvasive glucose monitoring; water as a relevant marker of glucose uptake in vivo

Abstract

With diabetes set to become the number 3 killer in the Western hemisphere and proportionally growing in other parts of the world, the subject of noninvasive monitoring of glucose dynamics in blood remains a "hot" topic, with the involvement of many groups worldwide. There is a plethora of techniques involved in this academic push, but the so-called multisensor system with an impedance-based core seems to feature increasingly strongly. However, the symmetrical structure of the glucose molecule and its shielding by the smaller dipoles of water would suggest that this option should be less enticing. Yet there is enough phenomenological evidence to suggest that impedance-based methods are truly sensitive to the biophysical effects of glucose variations in the blood. We have been trying to answer this very fundamental conundrum: "Why is impedance or dielectric spectroscopy sensitive to glucose concentration changes in the blood and why can this be done over a very broad frequency band, including microwaves?" The vistas for medical diagnostics are very enticing. There have been a significant number of papers published that look seriously at this problem. In this review, we want to summarize this body of research and the underlying mechanisms and propose a perspective toward utilizing the phenomena. It is our impression that the current world view on the dielectric response of glucose in solution, as outlined below, will support the further evolution and implementation toward practical noninvasive glucose monitoring solutions.

Review of Non-Invasive Glucose Sensing Techniques: Optical, Electrical and Breath Acetone

“…This conformational variation causes a change in the dielectric property of red blood cells. In vivo measurements demonstrated an increase in the dielectric permittivity of RBCs due to a decrease in glucose concentration [36]. Differences in size, morphology and distribution of RBCs between individuals result in differences in dielectric properties of tissue regardless of glucose concentration, and so affect the accuracy of glucose reading using dielectric based glucose measurement techniques.…”

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

“…Natural compounds serve as a base for the electrode arrays, as in the case of the wearable electronics (see Section 2.3.1 and Section 3.2 ). MSSs, based on metallic electrodes that record the dielectric properties of skin, can evaluate blood glucose level with acceptable accuracy, therefore, they have great commercial potential [ 103 , 104 , 105 , 106 , 107 ].…”

2019—A year in Biophysical Reviews

“…Aside from providing a clear summation of an interesting area of biochemistry this Review also holds importance for outlining the behavior of a novel set of drug targets in the protozoan agent responsible for malaria-a disease estimated to have infected over 200 million people worldwide, killing approximately half a million each year (W.H.O World Malaria Report 2019). Rounding out the Issue is a Review contributed from Israel on the subject of continuous blood glucose measurement in patients at risk for diabetes, based on dielectric spectroscopy (Caduff et al 2019). This Review first discusses why the technique can indeed be successful for measuring changes in the concentration of an uncharged molecule such as glucose (within the blood).…”

“…This Review first discusses why the technique can indeed be successful for measuring changes in the concentration of an uncharged molecule such as glucose (within the blood). By way of review, Caduff and coworkers outline the relevant theory and discuss potential experimental improvements for maximizing signal response (Caduff et al 2019).…”