Noninvasive monitoring of urine glucose using phase lock-in rotating analyzer polarimeter

Abstract Millions of people worldwide lose their lives each year due to diabetes, underscoring the critical need for early diagnosis to ensure healthier lives. In this study, we developed and applied, for the first time, a phase lock-in rotating analyzer (PLRA) polarimeter for the real-time and non-invasive monitoring of glucose levels in human urine. This novel device detects urine glucose level dependent polarization rotation as a phase shift in sinusoidal photovoltages generated by spatially distinct reference and sample beams, enabling precise glucose quantification. As the polarized laser beam interacts with glucose in human urine, the polarization rotates, causing a phase shift. This shift was then detected through phase-sensitive measurements, which capture sinusoidal variations in the photovoltages at two photodetectors. The calibration equations derived from fitting functions enable accurate estimation of glucose concentrations, achieving an impressive detection limit of 105 mg dl−1 for urine samples. The PLRA polarimeter demonstrated a linear detection response across physiological ranges, establishing its sensitivity, reliability, and practical applicability. By offering a cost-effective, innovative, and painless alternative to traditional blood-based tests, this method provides a pioneering tool for early glucose detection and improved diabetes management.