Healthy sleep normalises blood sugar: scientists explain the link

Scientists from the Westlake Life Sciences and Biomedicine Laboratory in China have reached these conclusions by analysing continuous glucose monitoring (CGM) data. This discovery is important for diabetes prevention and therapy.

Why it's important

Glucose regulation plays a critical role in maintaining metabolic health. Rapid fluctuations in blood sugar increase the risk of diabetes complications. While it is already known that lack of sleep negatively affects glucose metabolism, the long-term effects of sleep are poorly understood. The researchers set out to fill this gap.

The details of the study

The team studied sleep habits and their association with sugar fluctuations in 1,156 adult participants, aged 46 to 83 years, as part of a large cohort study in Guangdong Province, China. Over several years, participants regularly reported sleep duration and bedtime, and then wore CGM devices to measure glucose continuously for 14 days.

The researchers distinguished:

• Four sleep duration groups:

  • critically short (about 4 hours per night)
  • moderately short (about 5.5-6 hours)
  • slightly inadequate (about 7 hours)
  • adequate (8 hours)

• Two groups by bedtime:

  • early bedtime
  • late bedtime

What did the results show?

People with the shortest sleep had nearly 3% higher sugar fluctuations than those with adequate sleep. Those who went to bed late had a 1.18% higher rate. Problems with sugar regulation were particularly pronounced in those who slept little and also went to bed late.

Thus, the study showed that both the length of sleep and the time of falling asleep affect the stability of blood sugar levels. The combination of these factors is particularly harmful and increases the risk of diabetes.

The scientists' conclusions

The authors of the study emphasised: to prevent metabolic problems and reduce the risks of developing diabetes, it is necessary to sleep regularly and sufficiently, as well as to go to bed earlier. These simple measures can markedly improve sugar control and health.

Source: Luqi Shen et al, Trajectories of Sleep Duration, Sleep Onset Timing, and Continuous Glucose Monitoring in Adults, JAMA Network Open (2025). DOI: 10.1001/jamanetworkopen.2025.0114