Noninvasive subterahertz glucose monitoring using a communication inspired eye diagram

The global prevalence of diabetes mellitus (DM) continues to rise, highlighting the need for noninvasive, painless continuous blood glucose monitoring to support disease management and reduce long-term complications. Here, we report noninvasive subterahertz (sub-THz) glucose monitoring using communication-inspired eye diagram (sub-THz GlucoEye). The method detects distortion in the modulation pattern of sub-THz carrier signals reflected from the fingertip, resulting from relaxation time variations in the hydration water surrounding glucose molecules. These distortions are analyzed using multivariate regression analysis, based on variations in the modulation pattern's performance parameters represented in the three-dimensional eye diagram. Compared to conventional THz spectroscopy, which only measures THz radiation absorption, the sub-THz GlucoEye system shows enhanced linear correlation (R² = 0.98) between glucose-dependent features from modulation pattern changes and venous blood glucose concentrations. Results indicate strong consistency between glucose dynamics in venous blood and those at the fingertip during the mixed meal tolerance test, validated by 100% of glucose readings falling within Zones A and B based on Clarke's error grid analysis. This approach offers opportunities for real-time DM management and biomarker detection in future 6G integrated sensing and communication. Registry: Clinical Research Information Service, TRN: KCT0008820, Registration date: 17 June 2023.