Continuous glucose monitoring earbuds for periodic metabolic sensing

Abstract The applications of continuous glucose monitoring (CGM) are expanding into wellness, sports and preventive health, where metabolic information is particularly valuable around specific physiological events. However, conventional CGMs remain tailored to diabetes management, requiring around-the-clock, fixed wear even when periodic monitoring is sufficient. Here, we introduce the continuous glucose in-ear monitor (cGEM), an earbud-integrated platform for periodic, on-demand glucose monitoring from in-ear sweat. The cGEM establishes a skin–sensor interface through simple insertion and removal, enabling repeated monitoring without adhesive fixation. The platform integrates osmotic sweat extraction, microfluidic sampling and electrochemical glucose sensing while retaining audio playback. Computational modelling and in vitro characterization demonstrated controlled fluid transport and reliable glucose sensing. Dual-channel adaptive noise cancellation and personalized calibration reduce on-body signal artifacts and account for individual differences in blood–sweat glucose relationships. Despite periodic use, the cGEM showed close agreement with a continuously worn commercial CGM, achieving a mean absolute relative difference (MARD) of 8.79% across more than 50 h of monitoring. Repeated 1.5–5 h sessions captured event-specific glucose responses with a Pearson correlation coefficient of r = 0.88 relative to the commercial CGM. By integrating molecular sensing into widely used wireless earbuds, cGEM opens new possibilities for widespread adoption of metabolic monitoring, making it as accessible and routine as listening to music.