Studies have suggested that reduced sleep duration or interrupted sleep could increase insulin resistance and higher plasma glucose levels. However, causal relations are unclear from these data because of the potential biases from residual confounding (e.g., from physical activity and diet) and reverse causality (e.g., from nocturia and neuropathic pain).
A new study examined the effects of sleep traits on blood sugar levels. The study found that people who have difficulty getting to sleep or staying asleep had higher blood sugar levels. It offers evidence that insomnia is associated with higher Type-2 Diabetes risk. It also suggests that lifestyle or pharmacological treatments that improve insomnia could help to prevent or treat the condition.
For the study, scientists used the Mendelian randomization (MR) technique. MR analysis uses genetic variants as instrumental variables to appraise the causal effects of exposures on outcomes. Five sleep measures were considered: insomnia, sleep duration, daytime sleepiness, napping, and morning or evening preference (chronotype).
All these sleep measures were related to average blood sugar levels, assessed by a measure called HbA1c levels. Using MR, which groups people according to a genetic code randomly assigned at birth, allowed the scientists to remove any bias from the results.
The study, which involves more than 336,999 adults living in the UK, showed that people who reported that they often had difficulty getting to sleep or staying asleep had higher blood sugar levels than those who never reported, rarely, or only sometimes had these difficulties. There is no clear evidence found for the effect of other sleep traits on blood sugar levels.
According to scientists, this study could improve understanding of how sleep disturbance influences type 2 diabetes risk.
James Liu, Senior Research Associate in the Bristol Medical School (PHS) and MRC Integrative Epidemiology Unit (IEU) and corresponding author on the paper, said: “We estimated that an effective insomnia treatment could result in more glucose-lowering than an equivalent intervention, which reduces body weight by 14kg in a person of average height. This means around 27,300 UK adults, aged between 40- and 70-years-old, with frequent insomnia symptoms, would be free from having diabetes if their insomnia was treated.”
Dr. Faye Riley is Research Communications Manager at Diabetes UK. She said:Â “We know from past research that there’s a link between sleep and a person’s risk of type 2 diabetes, but it hasn’t been clear which comes first, bad sleep or higher blood sugars, or if other factors are at play.”
“This new study, funded by Diabetes UK, gives us important insights into the direction of the relationship between sleep and type 2 diabetes, suggesting that insufficient sleep can cause higher blood sugars levels and could play a direct role in developing type 2 diabetes. Knowing this could open up new approaches to help prevent or manage the condition.”
“However, it’s important to remember that type 2 diabetes is a complex condition with multiple risk factors. Eating a healthy balanced diet, being active, and getting enough sleep, are all essential components of good health for everyone – including those at risk of, or living with, type 2 diabetes.”
Scientists are further planning to determine the impact of insomnia treatment on blood glucose levels in people with and without diabetes. Through this, they could offer potential treatments for preventing diabetes.
Journal Reference:
- Junxi Liu, Rebecca C. Richmond et al. Assessing the Causal Role of Sleep Traits on Glycated Hemoglobin: A Mendelian Randomization Study. DOI: 10.2337/dc21-0089