New research uses a robust statistical method to investigate the relationship between insomnia and high blood sugar. It finds that treating insomnia could potentially prevent or even free some patients from type 2 diabetes.

Interview by Bushraa Khatib, MA

Junxi “James” Liu, PhD, BMed, was inspired to explore the link between insomnia and diabetes when he came across patients who had type 2 diabetes as well as poor sleep quality. “This led us to involve two people with diabetes who helped us design our research project,” says Liu, senior research associate at the Medical Research Council Integrative Epidemiology Unit, Bristol Medical School at the University of Bristol.

Liu and his team used Mendelian randomization analysis to go beyond studies that have found associations between sleep disturbance and higher sugar levels to determine whether an actual cause-and-effect relationship exists. The researchers found that frequent insomnia symptoms cause higher blood sugar levels and thus are implicated in causing type 2 diabetes.

“We believed that by identifying causal relationships, we might be able to direct clinicians to develop new interventions for sleep disturbance that could also treat or prevent type 2 diabetes,” he says.

Liu discussed the study with Sleep Review over email. The transcript has been lightly edited for clarity and style.

[Editor’s Note: Read the full study, Assessing the causal role of sleep traits on glycated hemoglobin: A Mendelian randomization study, in the journal Diabetes Care.] 

What was the most important finding from this study?

JL: We showed that people who reported that they often had insomnia—difficulty getting to sleep or staying asleep—had higher blood sugar levels than people who said they never, rarely, or only sometimes had these difficulties. We also found no clear evidence that other sleep traits, such as short sleep duration, caused higher sugar levels.

What surprised you?

JL: We were surprised that there was little evidence supporting short sleep duration as a cause of higher blood sugar levels. Previous studies had shown this link, but we knew that many of the methods used in prior studies could be potentially biased. In contrast, the evidence that insomnia caused higher sugar levels was robust in our study. Moreover, the level of robustness was somewhat surprising to us! Whichever way we looked at our data, the relationship between frequent insomnia symptoms and higher sugar levels was there.

What are the clinical implications of your research?

JL: Developing new interventions for insomnia would be expected to lower blood sugar levels, and this could have a useful role in treating or preventing type 2 diabetes. In our paper, we provided some insights into how effective an insomnia treatment might be. For example, we estimated that an effective insomnia treatment could lower blood sugar by more than that achieved by reducing body weight by 14 kg [~30 lbs]. We also estimated that around 27,300 middle-aged United Kingdom adults with insomnia would be free from having diabetes if their insomnia was adequately treated.

How would insomnia interventions work with weight loss and other treatments for type 2 diabetes?

JL: We would expect that insomnia treatments would have effects on lowering blood sugar levels independently of the effects of other treatments for diabetes. In other words, people with insomnia and diabetes could take their usual treatments as normal, but they might need less of them if their insomnia was adequately treated.

Junxi “James” Liu, PhD, BMed

How generalizable are your results to the broader population?

JL: We believe that our findings are very likely to be generalizable to a broader population, even though our study participants (UK Biobank) are a healthy group of people, on the whole. However, it would be helpful to repeat our study in younger people (less than 40 years of age) and in non-white people so that we could be more certain that our results are generalizable.

What further research should be done?

JL: We think that our research could now pave the way for clinical trials to be designed that test whether insomnia treatments can prevent or treat type 2 diabetes.

The Study:

Liu J, Richmond RC, Bowden J, et al. Assessing the causal role of sleep traits on glycated hemoglobin: A Mendelian randomization study. Diabetes Care. 2022 Apr;45(4):772-81.

Sleep researchers interested in participating in a Q&A should email editor[at] with a link to their relevant study.

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