Sleep Health and Glucose–Insulin Homeostasis in Adults: A Scoping Review

Background/Objectives: Type 2 diabetes (T2D) is a growing global health burden, affecting over 450 million people worldwide. Identifying modifiable behavioral risk factors impacting glucose metabolism is essential for T2D prevention. Sleep has emerged as a key, yet underrecognized determinant of cardiometabolic health. This scoping review aimed to synthesize evidence published between 2020 and 2025 evaluating the relationship between sleep and glucose–insulin homeostasis in adults. Methods: A systematic scoping review was conducted following PRISMA guidelines, using sleep and glucose/insulin-related keywords. Primary studies in English involving men and women (≥18 years) reporting objective or subjective sleep measures alongside glucose–insulin outcomes from PubMed were included. Results: In sum, 42 studies were retained out of 479 identified records. Several, but not all, studies showed that experimentally shortened sleep duration was associated with some impairment of glucose–insulin homeostasis, including elevated fasting glucose, fasting insulin, glycated hemoglobin, and insulin resistance. Conversely, extending sleep duration among short sleepers was associated with improved glycemic regulation. Studies including subjective assessments of sleep yielded similar associations, with poor sleep quality and short self-reported sleep duration linked to impaired glucose metabolism and higher T2D risk. Sleep disorders further compound dysregulation of glucose–insulin homeostasis, with dose-dependent effects observed for both obstructive sleep apnea severity and restless leg syndrome. Conclusions: Sleep is a promising target to improve glycemic control, although confirmatory clinical trials are needed. Screening for sleep disorders and promoting healthy sleep habits may be integrated for T2D risk reduction. Future research should assess multiple sleep dimensions in relation to glucose–insulin regulation to inform clinical practice.