Poor Sleep Worsens Blood Sugar Control

We hear enough about how sleep is one of the cornerstones of health. Do we really need more studies telling us how important it is, and how we need to get the standard 8 hours each night if we want to be happy and healthy?

Perhaps not, but it is still interesting to see new data linking sleep to different health parameters and studies that use novel methodologies to integrate sleep and personalized health. 

Using “real life” methods of analyzing sleep (such as activity monitoring) allows researchers to monitor how people sleep outside of the lab, which can perhaps be more applicable and is, for some people, more meaningful data than that gathered in a laboratory, where tightly-controlled conditions somewhat prevent generalizability.

New research published in the journal Diabetologia took this real-world approach to measuring both sleep metrics and blood glucose responses to meals in order to disentangle the complex relationship between sleep and metabolism. This is relevant because poor sleep has consistently been linked to impaired metabolic regulation and a variety of metabolic conditions including obesity and type II diabetes — the latter characterized by reduced insulin sensitivity which leads to elevated blood glucose and high postprandial (post meal) blood glucose levels.

Brief study methods

A total of 691 participants from the UK and USA (262 women) with an average age of ~45 participated in this study.

For a period of 14 days, all participants had their sleep and sleep characteristics monitored using a wrist-worn accelerometer, which was able to gather information on their total sleep duration, sleep efficiency, and sleep midpoint (i.e. the middle of their sleep period).

During this time, participants also consumed 8 different meals or “meal challenges” which included: an oral glucose tolerance test (OGTT), a high-carb meal, a high-fiber meal, a medium-fat and medium-carb meal, a high-fat meal (35g fat), a metabolic meal challenge, a high-protein meal, and a high fat meal (40g fat). The macronutrient composition of these meals can be seen in the graph below along with the average glucose response to these meals for all of the participants.

Everyone in this study was also fitted with a continuous blood glucose monitor (CGM) device, which took a blood glucose reading every 15 minutes throughout the study and, most importantly, after each breakfast meal (listed above). This data would allow calculation of the study’s primary outcome — the 2-hour glucose response (expressed as incremental area-under-the-curve) to each meal and, subsequently, how this glucose response is related to the participant’s sleep characteristics.


Total sleep time
  • There was no association between total sleep period and 2-hour glucose AUC
  • A significant interaction was found for sleep period and meal type: such that shorter sleep period was associated with higher 2-hour glucose after high-carb and high-fat meals
  • Getting more sleep than normal (within an individual) was associated with a lower glycemic response to high-carb and high-fat meals
Sleep efficiency
  • Greater sleep efficiency was associated with lower 2-hour glucose 
  • Achieving a greater sleep efficiency (within an individual) was associated with lower glycemic responses to a meal
Sleep midpoint
  • A later sleep midpoint (the result of a later bedtime) was associated with worse glycemic control (i.e. a higher glucose response) at breakfast

Thoughts & musings

It is somewhat interesting to see that out of all variables measured in this study, sleep duration (or total sleep period) was not associated with 2-hour glucose, as sleep duration has consistently been linked to several health outcomes. However, as the authors note, a lack of association in this study may be due to the fact that most participants actually had a sleep duration that fell within the recommended range and even the lowest quartile achieved around 6.87 hours of sleep per night.

The novel findings here are that sleep quality (assessed as sleep efficiency and sleep midpoint) were related to postprandial glycemic control — suggesting that it is not just how much one sleeps but, perhaps more importantly, how well, at what time, and the consistency to which one adheres to their sleep schedule. 

The latter point about consistency should be underscored. This study found that when someone goes to bed later than usual (thus having a later sleep midpoint), their glycemic control at breakfast the next day is worse. Going to bed (and waking up) at the same or similar time every day is emerging as one of the most important factors for sleep as it relates to metabolic health.

The application of these findings are pretty straightforward. Whether you’re a breakfast eater or not, getting the proper amount of sleep (though perhaps less important) and improving your sleep quality and consistency of your sleep schedule will lead to better glucose control surrounding meals — regardless of what those meals might be. Poor glucose control is a risk factor for diabetes but can also exert negative effects on aspects of aging, cardiovascular health, and cognition. Along with exercise, sleep seems to be at the center of optimizing metabolic health and is perhaps the thread that ties everything together.

Whether you choose to eat a high-carb diet, low-carb diet, or any variation in between, taking control of your sleep hygiene will help you live the healthiest and best life possible. With the availability of wearable devices (including CGMs) becoming widespread, anyone can have access to the type of data needed to see how lifestyle factors such as sleep and exercise affect their individual metrics. Thanks to technology, we can make evidence-based, n=1 decisions to take control of our own health.

Study cited

Tsereteli, N., Vallat, R., Fernandez-Tajes, J. et al. Impact of insufficient sleep on dysregulated blood glucose control under standardised meal conditions. Diabetologia (2021). https://doi.org/10.1007/s00125-021-05608-y

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