Caffeine and Diabetes: What You Should Know

Researchers have long been exploring the relationship between caffeine and diabetes. Some studies have shown that specific amounts of regular caffeine consumption (specifically coffee) may be linked to a lower risk of developing type 2 diabetes.

But because caffeine impacts blood sugar levels in the body, the same kind of caffeine intake may not be as beneficial in people who already have diabetes.

This article provides an overview of the evidence behind caffeine's potential protection against type 2 diabetes risk, how caffeine affects blood sugar and insulin levels, and healthy caffeine intake for diabetes.

Woman sitting in a coffee shop with another woman, drinking coffee
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Caffeine and Blood Sugar

Diabetes is a disease that affects the body's ability to process blood glucose (or blood sugar)—which is key for fueling the body with energy. When blood sugar levels aren't properly regulated, it can cause damage and other serious consequences in the body.

The food and drinks we consume—including caffeine—directly impact blood sugar levels. This means that dietary choices are especially important for people with diabetes. Research shows that caffeine consumption may make it more difficult for people with diabetes to manage their blood sugar levels.

One study found that people with type 2 diabetes who took a 250 milligram (mg) caffeine pill (roughly equivalent to two cups of coffee) in the morning and afternoon had higher blood sugar levels than on the days they did not consume caffeine.

Other research reviews suggest that caffeine intake increases blood sugar levels in people with diabetes and prolongs the time those levels remain high.

Caffeine, Blood Sugar, and Exercise

Exercise is a way to lower your blood sugar naturally. Studies suggest consuming caffeine before a workout might help reduce blood sugar levels even further for people with type 1 and type 2 diabetes. Remember that more intense physical activities (like sprinting or heavy weightlifting) can stimulate the stress hormone adrenaline, which can raise blood sugar levels.

Caffeine and Insulin

Insulin (a hormone naturally produced by the body) helps your cells use blood sugar for energy. In people with type 1 and type 2 diabetes, the body's insulin process doesn't work normally, causing dangerously high blood sugar levels that build up in the bloodstream.

In otherwise healthy adults, caffeine can still affect how the body responds to insulin, causing higher blood sugar levels after eating or drinking. For people with diabetes who already have issues processing or making insulin, caffeine consumption can trigger blood sugar levels that are way too high, potentially leading to other diabetes complications.

Caffeine and Risk of Type 2 Diabetes

A growing body of evidence suggests that regularly consuming caffeine (usually in the form of coffee) can lower a person's chances of developing type 2 diabetes.

Some research shows that increasing coffee intake to up to four cups per day can substantially reduce type 2 diabetes risk, mainly if the caffeine intake is over the years.

Studies also indicate that this protective factor is found in both caffeinated and decaffeinated coffee, likely due to coffee's naturally-occurring minerals and antioxidants that might help decrease disease-causing inflammation.

The addition of caffeine can make it more difficult for people with diabetes to manage blood sugar and insulin levels, so starting new caffeine habit is not recommended if you're currently living with the disease.

Caffeine and Type 1 Diabetes

People with type 1 diabetes have issues producing insulin, which means that caffeine will also affect them differently compared to a person who doesn't have diabetes.

One study found that adults with type 1 diabetes who drink five cups of coffee or more daily have a higher chance of developing metabolic syndrome. This condition increases the risk of other health issues like heart disease.

However, another study suggested that people with type 1 or type 2 diabetes can reduce their risk of hypoglycemia (a condition where your blood sugar levels drop too low) by consuming a smaller amount of caffeine before bed.

Healthy Caffeine Intake

Most healthy adults should not consume more than 400 milligrams (mg) of caffeine daily. For coffee drinkers, the equivalent would be roughly four to five cups of coffee. But keep in mind that caffeine is also present in other food and drink items, such as tea, soft drinks, dark chocolate, and energy drinks.

For people with diabetes, it's a good idea to check with a healthcare provider about the amount of caffeine intake that works for you, as caffeine can be a trigger for spiking your blood sugar. In addition, some people's blood sugar levels are naturally more sensitive to caffeine than others.

Whether caffeine is a staple in your diet or if you want to add it in, check with a healthcare provider first, especially if you have diabetes, for an individualized intake recommendation.

How Do You Take Your Coffee?

If you have diabetes and plain black coffee isn't your thing, ask your healthcare provider about the best coffee sweetener options for your diet. Sugar, syrups, milk, and creams are carbohydrates that can affect blood sugar levels. Experts recommend considering artificial sweeteners, which may be a safer alternative for people with diabetes.

Summary

Research has shown that consuming caffeine (specifically coffee) might lower the risk of developing type 2 diabetes. But for people who already have the disease, caffeine has the potential to do more harm than good due to its impact on blood sugar and insulin levels. If you have diabetes, check with a healthcare provider about your daily caffeine intake.

A Word From Verywell

Caffeine is just one dietary component that can impact people with diabetes. Other foods and beverages play a role in blood sugar and insulin levels, too. If you have access to a healthcare provider or nutritional consultant, they can help answer any questions about how caffeine may affect you and your overall health.

Frequently Asked Questions

  • Can drinking coffee prevent diabetes?

    Some research has suggested that regular coffee consumption may reduce your risk of developing type 2 diabetes. More studies are needed to understand the link between caffeine and diabetes risk protection.

  • How many cups of coffee are appropriate for people with diabetes?

    Experts believe blood sugar levels start to be impacted by caffeine at around 200 milligrams (mg), so roughly one to two cups of coffee might be appropriate for most adults with diabetes. Always ask a healthcare provider about suitable caffeine amounts for your individual dietary needs. 

  • Can I drink coffee before a fasting blood test?

    Experts recommend fasting (not eating or drinking) for at least eight hours before a blood sugar test. Any drink other than small sips of water as needed is usually not recommended. Check with your healthcare provider for their guidance.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cristina Mutchler
Cristina Mutchler is an award-winning journalist with more than a decade of experience in national media, specializing in health and wellness content.