August 3


How Does Caffeine Affect Blood Sugar and the Risk of Diabetes?

By Gabriela

August 3, 2022

The average American drinks about 474ml (two 8oz cups) of coffee a day. This amount of coffee contains about 280mg of caffeine. You may drink more or less coffee, but this beverage is not the only source of caffeine you take.

Other sources of caffeine include tea, energy drinks, chocolate, soda, and even some brands of ice cream. But, what’s caffeine exactly?

It is a stimulant found in some drinks and foods that accelerates the central nervous system.

For most people caffeine doesn’t seem to affect blood glucose levels significantly. So, they can consume up to 400mg of caffeine per day without any side effects.

However, when it comes to people with diabetes, caffeine shows a different reaction to their blood sugar levels.

Diabetes and Caffeine

Numerous studies show people with type 2 diabetes have different reactions to caffeine. Generally, it increases their insulin and blood sugar levels.

One research involved people with the disease who received 250mg of caffeine pills twice a day. Once at breakfast and another with their lunch. The amount of caffeine equals that in 2 cups of coffee with each meal.

The blood sugar levels of the participants were higher on days when they didn’t get caffeine by 8 percent. What’s more, their reading was increasing after each meal.

These results are proof that caffeine has a significant impact on the body’s response to the hormone which lets sugar inside the cells and gets transformed it into energy.  This hormone is insulin.

Caffeine can reduce your body’s sensitivity to insulin. In other words, the reaction of your cells to insulin is different in presence of caffeine. Your cells are no longer able to absorb the right amount of sugar from your blood after you’ve had your meals.

This, in turn, increases your body’s production of insulin, so you end up with higher levels after eating or drinking.

People with type 2 diabetes can’t use insulin properly. Their blood glucose increases higher than normal after meals. And, by eating or drinking something that contains caffeine they only make it harder to bring back their levels of blood sugar to normal.

Over time, this could increase the risk of diabetes complications such as heart disease or nerve damage.

How Much Caffeine Is Too Much

Drinking 3 or 4 cups of black tea or 1 or 2 cups of brewed coffee means consuming 200 mg of caffeine. This is the amount of caffeine that affects your blood sugar levels.

Even though this is the general amount of caffeine that shows effects on blood glucose, it also depends on factors like weight and age.

Nevertheless, this doesn’t mean that people with diabetes who drink coffee regularly have higher levels of blood sugar than those who aren’t. Researchers believe that over time, the human body gets used to the amount of caffeine you take regularly.

However, others think caffeine could still raise the levels of blood sugar even if you drink a cup of coffee every morning.

Still, you should consult your doctor to discover if caffeine causes spikes in your blood glucose. You can also test your blood glucose after drinking the first cup of coffee. Then, avoid coffee for a few days and test it once again to see its effects on your blood glucose.

Coffee and the Risk of Diabetes

You might be surprised, but many studies show that coffee reduces the risk of developing type 2 diabetes. In particular, one Harvard School of Public Health study showed that drinking one cup of coffee a day more than you usually do for 4 years, reduces the risk of type 2 diabetes by 11%.


If you already have diabetes, limit your caffeine intake. But, it’s always best to consult a doctor or test your blood sugar levels to see how your body reacts to this stimulant.

Source WebMD | Mayo Clinic | Medical News Today


  • Gabriela

    Co-Founder & Editor-in-Chief of Diabetes Health Page, Fitness trainer and instructor has dedicated her career to educating and informing people for over 10 years. As one of the most passionate diabetes advocates, Gabi has worked tirelessly to ensure that those people receive the education and support they need to properly manage their diabetes and achieve their health, fitness and weight loss goals.

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