Does Caffeine Impact Blood Sugar?

One thing that people with type 1 diabetes (T1D) know for sure is that blood sugar fluctuations can have many causes. 

What about caffeine? Have you ever noticed any fluctuations in your blood sugar after drinking a cup of coffee, a cup of tea or an energy drink (e.g., RedBull, Monster Energy)?

Obviously, any beverage that contains sugar will raise your blood sugar. However, some people have reported rising blood sugar levels after consuming one of these beverages with no sugar. So, does caffeine alone impact blood sugar? 

The impact of caffeine

Studies that looked at the impact of caffeine on blood sugar are generally inconclusive, so it’s difficult to identify any kind of broader trend. 

However, two facts can be observed:

  • Caffeine might improve hypoglycemia awareness. A study conducted in 2005 by the American Diabetes Association found that drinking a little bit of coffee before going to bed might reduce the risk of nighttime hypoglycemia. While it may seem counterintuitive to drink coffee at night, hypoglycemia awareness seems to have improved in some people after they added caffeine to their diet.
  • Caffeine might affect blood sugar levels. Some studies observed that caffeine might cause varying levels of blood sugar fluctuations, especially in people with type 2 diabetes. Higher blood sugar levels related to the consumption of caffeine have been reported. Caffeine triggers the release of adrenaline, which raises blood sugar levels. While it may be difficult to draw conclusions on the broader impact of caffeine on blood sugar levels, consuming the same amount of caffeine every day might help managing blood sugar levels. 

Other factors at play

Caffeine is only one of the many factors that can impact blood sugar levels.

  • Dawn phenomenon: Can you really tell whether your higher blood sugar levels in the morning are due to caffeine or the dawn phenomenon?  
  • Lack of sleep: Lack of sleep alone can result in higher blood sugar levels due to a stronger insulin resistance (i.e., the same dose of insulin is not as effective).  
  • Caffeine tolerance: The level of caffeine tolerance varies from person to person. Symptoms such as palpitations, heartburn and stomach ache can appear regardless of the amount of caffeine consumed. So, the impact of caffeine on blood sugar levels may be different for each person. 

As you can see, it’s rather difficult to have a complete and exact picture of how caffeine impacts blood sugar levels! But if you feel like your morning coffee might be messing with your blood sugar, you’re not alone! 

To better understand how caffeine affects you, the best thing you can do is experiment and observe while considering other factors such as the accuracy of carb counting and the time of day. 


  • Caffeine: Does it affect blood sugar?, consulté le 16 mars 2021, https://www.mayoclinic.org/diseases-conditions/type-2-diabetes/expert-answers/blood-sugar/faq-20057941
  • Systematic review of randomised controlled trials of the effects of caffeine or caffeinated drinks on blood glucose concentrations and insulin sensitivity in people with diabetes mellitusN WhiteheadJournal of Human Nutrition and Dietetics 26(2):111Wiley 2013, 0952-387110.1111/jhn.12033
  • Tolulope Olateju, Joseph Begley, Daniel J. Green, David Kerr,Physiological and Glycemic Responses Following Acute Ingestion of a Popular Functional Drink in Patients with Type 1 Diabetes,Canadian Journal of Diabetes,Volume 39, Issue 1,2015,Pages 78-82,
  • Watson, J M et al. “Influence of caffeine on the frequency and perception of hypoglycemia in free-living patients with type 1 diabetes.” Diabetes care vol. 23,4 (2000): 455-9. doi:10.2337/diacare.23.4.455
  • Richardson, Tristan et al. “Influence of caffeine on frequency of hypoglycemia detected by continuous interstitial glucose monitoring system in patients with long-standing type 1 diabetes.” Diabetes care vol. 28,6 (2005): 1316-20. doi:10.2337/diacare.28.6.1316

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