Suboptimal sleep and abnormal blood glucose levels are independently recognized contributors to long-term health risks. A large prospective cohort study titled “Association of Sleep and Glycaemic Status with All-Cause Mortality” by Andi Xu and colleagues examined whether sleep duration and sleep disorders influence mortality differently among individuals with normoglycaemia, prediabetes, and diabetes.

The findings suggest that sleep patterns may play an important role in long-term health outcomes, particularly among individuals with impaired glucose regulation.

Study Design and Population

The study included:

• 363,863 participants with normal glucose levels

• 144,602 participants with prediabetes

• 25,773 participants with diabetes

Over a median follow-up period of 19 years, researchers recorded 52,208 deaths.

Participants were categorized based on their self-reported sleep duration:

• Less than 6 hours

• 6–8 hours (reference group)

• More than 8 hours

The study also assessed the presence of diagnosed sleep disorders.

Key Findings on Sleep Duration and Mortality

Compared to individuals sleeping 6–8 hours per night, the study found:

Short Sleep (<6 hours)

• Among individuals with normoglycaemia, short sleep was associated with a slightly higher risk of all-cause mortality

  • Hazard Ratio (HR) = 1.05

  • 95% Confidence Interval (CI) = 1.02–1.08

Short sleep did not show similarly strong associations in prediabetes and diabetes groups.

Long Sleep (>8 hours)

Long sleep duration was associated with increased mortality risk across all glycaemic categories:

• Normoglycaemia: HR = 1.19 (95% CI = 1.15–1.24)

• Prediabetes: HR = 1.24 (95% CI = 1.19–1.30)

• Diabetes: HR = 1.29 (95% CI = 1.22–1.36)

The risk appeared progressively higher among individuals with impaired glucose regulation.

Sleep Disorders and Mortality Risk

The presence of sleep disorders was also associated with increased mortality:

• Prediabetes: HR = 1.04 (95% CI = 1.01–1.07)

• Diabetes: HR = 1.07 (95% CI = 1.02–1.11)

The association was not statistically emphasized among those with normoglycaemia.

See also: Seniors With Prediabetes Should Not Fret Too Much About Diabetes

How Sleep May Influence Blood Sugar Regulation

Although the study was observational and does not establish causation, existing scientific evidence provides biological plausibility for the relationship between poor sleep and impaired glucose metabolism.

Sleep deprivation has been shown in prior research to:

• Increase insulin resistance

• Elevate cortisol (stress hormone) levels

• Disrupt circadian rhythms that regulate glucose metabolism

• Affect appetite-regulating hormones such as leptin and ghrelin

Short or fragmented sleep may impair the body’s ability to regulate blood glucose efficiently, potentially contributing to prediabetes, particularly when combined with other risk factors such as obesity and sedentary lifestyle.

Long sleep duration has also been associated in some studies with underlying chronic illness, systemic inflammation, or poor overall health status, which may partly explain its stronger association with mortality.

Prediabetes and Morning Glucose Dysregulation

Prediabetes is characterized by elevated fasting blood glucose levels that are not yet high enough for a diabetes diagnosis. Disrupted sleep patterns may influence early morning glucose levels through hormonal shifts occurring overnight.

While this study did not specifically measure morning glucose fluctuations, its findings reinforce the broader association between abnormal sleep patterns and impaired glycaemic regulation.

Observational Nature and Study Limitations

The researchers emphasized that the study is observational. Therefore:

• It cannot establish direct causation.

• Sleep duration was self-reported.

• Underlying health conditions may influence both sleep patterns and mortality risk.

Despite these limitations, the large sample size and long follow-up strengthen the reliability of observed associations.

Clinical and Public Health Implications

The findings suggest that sleep assessment may serve as an additional factor in risk stratification for individuals with impaired glucose regulation.

Healthcare providers may consider discussing sleep duration and sleep quality when evaluating patients at risk for prediabetes or diabetes progression.

However, further interventional research is needed to determine whether improving sleep can directly reduce mortality or glycaemic progression.

Conclusion

In a large cohort of over 530,000 adults followed for nearly two decades, long sleep duration and sleep disorders were associated with increased all-cause mortality, particularly among individuals with prediabetes and diabetes. Short sleep duration was linked to modestly higher mortality risk among individuals with normoglycaemia.

The findings highlight the potential role of sleep patterns in metabolic health and long-term outcomes.

Reference

1. Xu, Andi, Cao Zhi, Sicong Wang, Fei Cai, Zuhui Zhang, David Ta-Wei Chu, Wenyuan Li, Chi Pang Wen, and Xifeng Wu. “Association of Sleep and Glycaemic Status with All-Cause Mortality: A Prospective Cohort Study.” Journal of Global Health, January 2026. https://jogh.org/wp-content/uploads/2026/01/jogh-16-04002n.pdf.