Caffeine and Diabetes

woman enjoying her coffee

Clinically reviewed by Kathleen Stanley, CDCES, RDN, LD, MSEd, BC-ADM, MLDE.

Does caffeine affect blood sugar? If you have diabetes or know someone who does, that question may have crossed your mind; it is a good one since most Americans consume caffeine in some form every day. That includes coffee, tea, sodas, energy drinks, chocolate, and other sources. 

Studies suggest it is safe for healthy adults to consume up to 400 milligrams of caffeine daily. However, caffeine may not be good for people with diabetes. 

Type 2 Diabetes and Caffeine

When people with diabetes consume caffeine, the effect on their blood sugar levels is unpredictable. Evidence suggests there is a correlation between caffeine resulting in either higher or lower blood sugars, dependent upon individual.

Caffeine affects everyone differently. But in some cases, approximately 200 to 250 milligrams of caffeine (the amount in one or two 8-ounce cups of black, brewed coffee) can significantly impact their blood sugar levels. Consequently, if you have diabetes and find it challenging to manage your blood sugar, it is advisable to minimize your caffeine intake. 

How Does Caffeine Affect Blood Sugar Levels?

Research on the relationship between caffeine consumption and blood sugar is ongoing. However, scientists speculate that some of the forces at work may include:

  • Caffeine increases the level of stress hormones like epinephrine (also called adrenaline), and those substances can temporarily reduce the ability of cells to process sugar. These hormones may also increase insulin resistance.
  • Caffeine blocks adenosine, a protein molecule that plays a crucial role in insulin production. It also affects how cells respond to insulin.
  • Caffeine inhibits sleep. Drinking too much caffeine or consuming it too close to bedtime can make it hard to sleep, and sleep deprivation decreases insulin sensitivity. 

Therefore, it appears that caffeine’s impact on blood sugar levels is complex and multifaceted.  

Proper Diabetes Management Is Essential to Good Health

People who have been managing their diabetes for a long time understand what is at stake. If you are newly diagnosed, it is crucial to acknowledge that allowing your blood sugar to be outside the normal range frequently or continually can lead to a wide variety of severe health problems. They include:

  • Heart disease
  • Vision loss
  • Kidney failure
  • Cognitive issues
  • Nerve damage
  • Foot infections

Generally speaking, the impact of untreated diabetes on your body can lead to lifelong health ailments.

Occasionally experiencing fluctuating blood sugars, both higher and lower as a result of consuming caffeine probably won’t have a noticeable negative effect on your overall health. But if you consume caffeine every day and each time it adversely affects your blood sugar level, that is a side effect worth addressing and working towards managing.

Learn More About Caffeine and Diabetes from Baptist Health

If you have diabetes and consume caffeine, you should talk with your doctor about the possible effects it may have on your blood sugar levels. They can provide guidance on how to monitor and modify your caffeine intake if necessary. 

A great place to start if you want more information on how food and drink impact blood sugar, is to contact one of our diabetes educators or registered dietitians. 


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