An Approach for Noninvasive Blood Glucose Monitoring Based on Bioimpedance Difference Considering Blood Volume Pulsation

Noninvasive blood glucose monitoring (NBGM) provides a promising solution for patients with diabetes with the advantages of painless and continuous monitoring. To better characterize the response of glucose to radio-frequency (RF) signals at low frequencies, the conductivity and relative permittivity of aqueous solutions with different glucose concentrations were obtained by the use of an impedance analyzer in the frequency range of 1 kHz to 1 MHz. Furthermore, considering the blood volume pulsation in cardiac cycle, a new approach based on measuring bioimpedance was presented for NBGM in this paper. For this purpose, an inhomogeneous arm model, which consists of three tissue layers (i.e., blood, blood vessel, and other relevant tissues), was proposed to validate the aforementioned approach. Furthermore, the measurements were carried out by means of in vitro experiment and in vivo studies, respectively. The results showed that as the glucose concentration increased, the conductivity of aqueous solutions decreased when the frequency of RF signal was below 1 MHz. However, the relative permittivity was almost insensitive to glucose concentration. The simulation result of the arm model showed that as the glucose concentration increased, the bioimpedance difference of blood volume decreased. This was supported by both in vitro and in vivo experiments. We therefore suggest that the proposed approach for NBGM has potentials in practical applications.