Radar-Based Monitoring for Non-Contact Detection of Nocturnal Hypoglycemia in Diabetes: A Review

Radar technology has emerged as a promising tool for contactless monitoring of sleep physiology and related disorders. Nocturnal hypoglycemia is a critical safety concern in people with diabetes, particularly in vulnerable populations such as children, older adults, and individuals in long-term care, where body-worn devices are often not used. To assess the feasibility of radar-based hypoglycemia detection, we conducted a scoping review of studies published between January 2007 and July 2025 that investigated radar monitoring of physiological parameters during sleep or sleep-related disorders with overlapping autonomic and motor physiological signatures. A structured search and data extraction were performed, covering bibliographic, technical, clinical, and performance variables. Across 78 studies, radar was consistently validated for respiration, heart rate and heart rate variability, body movement, and posture, with reported accuracies frequently exceeding 90%. Sleep staging showed lower but meaningful performance (63-85%). Disease-focused applications demonstrated robust results in sleep-disordered breathing, including obstructive sleep apnea and sleep apnea-hypopnea syndrome, as well as initial explorations in asthma, insomnia, and seizure detection. Together, these studies establish radar as a reliable, contactless sleep monitoring modality for respiration, HR and HRV, movement, posture, and sleep staging, which are physiological signals known to change during nocturnal hypoglycemia. Building on this foundation, radar is well positioned to enable indirect nocturnal hypoglycemia detection, especially where wearables are not feasible. Establishing clinical performance now requires studies that pair radar with glucose measurements and report event level diagnostic accuracy.