Do short sleep duration and insomnia increase insulin resistance and raise fasting insulin and glucose?

Clinical evidence

• Insulin resistance and hyperinsulinemia: Extensive randomized crossover trials and prospective cohorts demonstrate that short sleep duration and insomnia-like disturbances directly impair insulin sensitivity. For example, restricting sleep in women to approximately 6.2 hours per night over a multi-week period significantly elevates fasting insulin and homeostatic model assessment of insulin resistance (HOMA-IR) independently of changes in body fat. In adolescent populations, acute partial sleep deprivation has been shown to trigger up to a 59% increase in fasting insulin, whereas extending sleep in habitual short sleepers successfully reverses these metabolic deficits.
• Impaired fasting glucose: Longitudinal tracking and epidemiologic cohorts reveal that habitual short sleep (less than 7 hours per night) correlates with a 1.46 to 2.5-fold increase in the odds of developing impaired fasting glucose (IFG). Severe sleep fragmentation and subjective insomnia symptoms further compound this risk, showing strong predictive links to incident type 2 diabetes.

Mechanistic explanations

• HPA-axis dysfunction: Insufficient or fragmented sleep disrupts the normal circadian rhythm of the hypothalamic-pituitary-adrenal (HPA) axis, elevating evening cortisol levels and shifting cortisol secretory phases. Controlled hormone-clamping experiments confirm that this elevated cortisol drive accounts for approximately half of the insulin resistance induced by sleep restriction.
• Sympathetic nervous system hyperactivation: Sleep loss shifts the autonomic balance toward sympathetic dominance, elevating circulating epinephrine and norepinephrine.
• Lipotoxicity and signaling disruption: Hyperactivity of both the sympathetic nervous system and the HPA axis accelerates adipocyte lipolysis, leading to an influx of circulating non-esterified fatty acids (NEFAs). These elevated NEFAs directly impair insulin-stimulated glucose uptake in skeletal muscle and stimulate excess hepatic glucose production. Over time, chronic sleep fragmentation also recruits low-grade systemic inflammatory pathways that further degrade insulin receptor substrate signaling.

Bottom line

Short sleep duration and insomnia are clinically and mechanistically proven to cause insulin resistance, elevate fasting insulin, and raise fasting glucose. This metabolic decline is driven by HPA-axis and sympathetic nervous system hyperactivity, elevated free fatty acids, and impaired peripheral insulin signaling—effects that can be partially mitigated or reversed by sleep extension.