Short Sleep and Type 2 Diabetes Risk: Findings from 12.5 Years of Follow-up in the UK Biobank
In March 2024,
JAMA Network Open published
a large-scale prospective cohort study that examined the link between habitual sleep duration and therisk of developing type 2 diabetes (T2D). Based on data from 247,867 adults enrolled in the UK Biobank, researchers followed participants for a median of 12.5 years, making this one of the most comprehensive studies to date on sleep and metabolic health.
The results suggest that short sleep-especially extreme short sleep-is independently associated with a significantly increased risk of type 2 diabetes, even after adjusting for known lifestyle and demographic risk factors.
Study Overview
Led by Dr. Fang Yang of Fudan University, the research team focused on adults aged 38 to 71 who did not have diabetes at baseline. Participants reported their usual nightly sleep duration along with lifestyle and dietary habits. Incident type 2 diabetes cases were confirmed using linked medical records.
Over the follow-up period:
- 7,889 participants (3.2%) developed type 2 diabetes.
Sleep duration was categorized into five groups: 3–4 hours, 5 hours, 6 hours, 7–8 hours (reference group), and ≥9 hours.
Key Results
Compared with participants who slept 7–8 hours per night:
- Sleeping 5 hours was associated with a 16% higher risk of developing T2D (HR 1.16; 95% CI, 1.09–1.24).
- Sleeping 3–4 hours (extreme short sleep) was linked to a 41% higher risk (HR 1.41; 95% CI, 1.23–1.61).
- 6 hours of sleep showed a more modest but still statistically significant risk (HR 1.10; 95% CI, 1.06–1.14).
- Long sleep (≥9 hours) was not significantly associated with T2D risk in either direction.
These associations held true after adjustments for age, sex, race/ethnicity, BMI, physical activity, smoking status, alcohol consumption, family history of diabetes, socioeconomic status, and other potential confounders.
Biological Mechanisms
Several biological pathways may explain how short sleep contributes to the development of type 2 diabetes. Inadequate sleep can impair the body’s ability to regulate glucose by reducing insulin sensitivity, which in turn makes it harder for cells to absorb glucose from the bloodstream. Additionally, insufficient sleep activates the sympathetic nervous system and increases cortisol levels, which further disrupts glucose metabolism. Short sleep is also associated with hormonal changes, such as decreased leptin and increased ghrelin, leading to increased appetite and a preference for high-calorie foods. Finally, sleep deprivation may promote chronic low-grade inflammation, which plays a key role in insulin resistance. Together, these processes create a metabolic environment that favors the onset of type 2 diabetes.
Sleep and Diet: Independent Contributors
To explore the role of diet, researchers evaluated participants’ eating habits using the Healthful Plant-Based Diet Index (hPDI). The Healthful Plant-Based Diet Index (hPDI) is a dietary index that measures adherence to a plant-based diet emphasizing healthy plant foods such as fruits, vegetables, whole grains, legumes, and nuts. It assigns higher scores for consumption of these foods and lower scores for intake of less healthy plant foods and all animal-based foods.
As expected, individuals with higher hPDI scores—indicating better adherence to a plant-based, whole-food diet-had lower overall T2D risk.
However, the analysis revealed no statistically significant interaction between sleep duration and diet quality. That is, short sleep increased the risk of diabetes regardless of dietary quality.
“We found no statistically significant multiplicative or additive interaction between sleep duration and hPDI score in relation to T2D risk,” the authors wrote.
This finding underscores that sleep and diet are independent lifestyle factors-each relevant to diabetes prevention but not compensating for one another’s effects.
Public Health Implications
This study confirms short sleep, particularly when habitual and extreme, as an independent, modifiable risk factor for type 2 diabetes. Importantly, the association was observed even among individuals with a healthy diet, active lifestyle, and normal weight.
These findings highlight the need to include sleep health alongside diet and exercise in public health recommendations for diabetes prevention.
Key implications:
- Adults should aim for 7–8 hours of sleep per night as part of overall metabolic care.
- Sleep screening should be considered in clinical risk assessments for diabetes.
- Public health initiatives should integrate sleep education and sleep hygiene practices in broader lifestyle programs.
Recommendations
For individuals and clinicians alike, this study offers several actionable insights:
- Prioritize consistent, sufficient sleep—ideally 7–8 hours each night.
- Maintain healthy sleep habits (e.g., fixed bedtime, screen-free evenings, dark and quiet sleep environments).
- Recognize extreme short sleep (≤4 hours) as a clinical red flag.
- Combine sleep improvement with evidence-based dietary and physical activity guidelines to reduce diabetes risk.
