Review of non-invasive continuous glucose monitoring based on impedance spectroscopy

The incidence of diabetes is increasing at an alarming rate worldwide, and glucose monitoring is critical to diabetes management. Non-invasive continuous blood glucose monitoring is highly sought after for diabetes management. While enzyme based approaches already have commercial products, they are invasive, inconvenient for patients to use, and cannot be continuous. Non-invasive glucose detection by spectroscopy methods have garnered much interest in recent years, however, still facing many challenges to be adopted for clinical applications. Among spectroscopy methods, electrical impedance methods have the advantages of being low cost and user-friendly. This review summarizes recent advances in noninvasive continuous glucose monitoring based on skin impedance measurement by electrical impedance spectroscopy (EIS), with emphasis on the devices that can potentially be integrated into wearable platforms. The discussion includes physical designs of bioimpedance sensors, signal measurement strategies, modeling and parameter estimation methods to extract blood glucose levels, and portable system designs. At the end, the challenges of EIS based glucose estimation devices and the trend of non-invasive glucose monitoring techniques are discussed. (C) 2020 Elsevier B.V. All rights reserved.