The Effects of Sleep on Blood Sugar - Type 2 Diabetes

Sleep deprivation disrupts the glucose metabolism in your body and may increase the risk of developing Type 2 diabetes. There are hormones in your body which play major roles in regulating sleep cycles and blood sugar levels. During sleep, the body shuts down non-essential functions to conserve energy and resources. Your body secretes the hormones melatonin and cortisol that put you to sleep and save energy. In this article, we will discuss the roles of these hormones and how they link your sleep and blood sugar level.1


Your body releases cortisol under stress. Cortisol stimulates the breakdown of muscle tissue and  promotes the formation of free radicals (elements that can damage cells). Cortisol also has an insulin-like effect on blood sugar level.2

The release of cortisol in blood boosts glucose production in the liver. This increases the release of glucose into the bloodstream, keeping blood sugar levels more stable during sleep.2

The less you sleep, the lesser the release of cortisol, slowing down the glucose metabolism in your body. Frequent lack of sleep may increase your chances of developing type 2 diabetes in the long run.


Your body secretes melatonin at night. As you begin to fall asleep, melatonin production increases, making you calm and relaxed.

Studies suggest there is a strong association between melatonin and insulin. As your body secretes melatonin, the chemicals responsible for insulin secretions become active as well.3

Those with more melatonin have better insulin sensitivity than those with less, allowing more control over the amount of glucose absorbed into their bloodstream from food without causing spikes in insulin levels.3

The Importance of Sleep

  • A growing body of evidence indicates that lack of sleep may contribute to the risk of type 2 diabetes. 
  • Sleep plays an integral role in a number of metabolic functions especially with how glucose (sugar) is metabolised. In one study, individuals were subjected to 4 hours in bed for 6 nights and after 6 nights of sleep deprivation, individuals had a reduced ability to clear glucose from the body by 40%.4
  • Epidemiological data suggest that chronic short sleep duration increases the risk of type 2 diabetes. While lack of sleep alters how glucose is metabolised there are other important factors that occur.5
  • Some of these factors include an increase in appetite due to both the hormones leptin and ghrelin. Leptin is an appetite suppressant and ghrelin is released by the stomach and promotes feelings of hunger. After a short sleep, leptin has been shown to be suppressed and ghrelin has been reported to be increased. This leads to increased consumption of food and can lead to excessive weight gain, one of the risk factors for type 2 diabetes.6

Tips for a good night’s sleep

  • Stick to a sleep schedule. Try going to bed at the same time and waking up at the same time every day.
  • Engage in physical activity for at least 30 minutes on five days of the week and avoid exercising close to bedtime.
  • Avoid caffeinated drinks like tea and coffee for at least 6 hours before bedtime.
  • Avoid drinking alcohol, as it limits the amount of deep sleep you get.
  • Choose a lighter evening meal to help with your digestion and improve your sleep quality. Swap carbohydrate foods such as white rice, white bread, and white pasta for whole grain/whole-wheat alternatives. 
  • Make your room sleep-friendly by creating a dark, cool and technology-free room.  Body temperature is at its highest before you sleep. A cool room suits your body temperature needs, and can help you drift off quicker and get better quality sleep. 


  1. Aldabal, L., & Bahammam, A. S. (2011). Metabolic, endocrine, and immune consequences of sleep deprivation. The open respiratory medicine journal, 5, 31–43. doi:10.2174/1874306401105010031
  2. Joseph, J. J., & Golden, S. H. (2017). Cortisol dysregulation: the bidirectional link between stress, depression, and type 2 diabetes mellitus. Annals of the New York Academy of Sciences, 1391(1), 20–34. doi:10.1111/nyas.13217
  3. Garaulet, M., Qian, J., Florez, J. C., Arendt, J., Saxena, R., & Scheer, F. (2020). Melatonin Effects on Glucose Metabolism: Time To Unlock the Controversy. Trends in endocrinology and metabolism: TEM, 31(3), 192–204. doi:10.1016/j.tem.2019.11.011
  4. Knutson, K. L., & Van Cauter, E. (2008). Associations between sleep loss and increased risk of obesity and diabetes. Annals of the New York Academy of Sciences, 1129, 287–304. doi:10.1196/annals.1417.033
  5. Grandner, M. A., Seixas, A., Shetty, S., & Shenoy, S. (2016). Sleep Duration and Diabetes Risk: Population Trends and Potential Mechanisms. Current diabetes reports, 16(11), 106. doi:10.1007/s11892-016-0805-8
  6. Physiology, Obesity Neurohormonal Appetite And Satiety Control [Internet] Treasure Island (FL): StatPearls Publishing. [cited 22 July 2022]. Available at:

Rodrigo Montenegro

Master of Science - MSc. Neuroscience, Universidad Isabel I, Spain

Rodrigo Montenegro is a Neuroscientist with Sleep Medicine specialization from Oxford University. Rodrigo has worked as a lead Neuroscientist developing a clinical grade sleep-headband and as a consultant in applied medical neuromodulation technologies. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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