July 10


How Does Coffee Affect Blood Sugar?

By Gabriela

July 10, 2017

In the past, coffee was believed to be bad for overall health. But nowadays, there is growing evidence that the coffee might actually be beneficial and help protect from Parkinson’s disease, depression, and liver disease.

One study came to the conclusion that if we increase the intake of coffee that might be beneficial, which was contrary to the previous belief.

In fact, increased intake of coffee can reduce the risk of developing type 2 diabetes. This is great news for people who cannot go through the day or simply start the day without a cup of coffee.

However, people who already have this chronic disease should be careful. Why? Because in this case, the coffee could have negative effects.

It does not matter if we have the disease, or we cannot start our day without coffee, or maybe we are trying to reduce the risk of developing the disease, we need to know how coffee affects us.

Coffee – The Potential Prevention of Diabetes

Coffee can be beneficial for different things, but it mostly depends on the case.

Diabetologia published a study that started to cause discussion. The Harvard researchers did extended research that lasted about 20 years. In those 20 years, they tracked around 100,000 people.

However, they only concentrated on a period of 4 years. The came to the discovery that people that increased their intake of coffee just by more than 1 cup on a daily basis actually ended up having 11% reduction in the risk of developing type 2 diabetes (T2D).

And on the other hand, people that reduced the intake of coffee on a daily basis ended up with an increased risk of developing the disease by 17 %.

It was the same for those that drank tea. However, why the coffee has a big impact when it comes to developing this chronic condition, is still unknown.

In fact, caffeine may not do the job here. Because in the short term what the caffeine does is that it actually increases the insulin and the glucose levels.

Coffee and Its Effect on Insulin and Glucose

In 2014, Diabetes Care published a study that reports a crucial thing for those with type 2 diabetes – if they drink coffee before they eat, it can lead to higher blood glucose after the meal.

In addition, it showed that there is an increase in the resistance of insulin, which means that coffee is good for protection against developing T2D. But it may be dangerous for people that already have this type of disease.

Besides caffeine, coffee contains other ingredients as well. Some of the ingredients may be the reason why in the 2014 study the coffee showed a protective effect.

Furthermore, the consummation of caffeinated coffee for a long time may result in changing its effect when it comes to insulin and glucose sensitivity.

The reason why coffee could have a protective effect might be the tolerance from its long term drinking.

A different study in 2004 took a look at the mid-range impact on healthy people. They drank 1 liter of coffee on a daily basis, but later they did not drink this beverage for 4 weeks.

In the end, the researchers found that people that consumed coffee actually end up having higher amounts of insulin than those that did not.

That happened even when there was fasting. When someone has T2D, the body attempts to produce more insulin to clear the sugar from the bloodstream.

In prolonged consumption, there is the tolerance effect. However, for that to happen 4 weeks are just not enough.

There is the apparent difference in how people without and people with the disease respond to caffeine and coffee.

There was another study at the Duke University about coffee. The researchers had individuals with T2D that were regular coffee drinkers.

They monitored the blood sugar of these coffee drinkers when they were doing their everyday activities. It was shown that during the day, their blood sugar would soar just after drinking coffee.

Their blood sugar was higher when they drank coffee than it was when they did not. So one more, there is the same conclusion.

Caffeine acts as a protector if we do not have the disease, but can be hazardous in case we already have type 2 diabetes.

Coffee and Its Health Benefits

Still, there are plenty of benefits from the coffee. The past studies did not consider the other risk factors of the people that drank coffee when they were doing the study.

Furthermore, the new studies made with control of the risk factors show that coffee has other benefits.

The Coffee Can Help Protect Against:

  • Parkinson’s disease
  • Gallstones
  • Liver disease (plus liver cancer)
  • Alzheimer’s disease
  • Gout

According to the studies, coffee can increase the ability to think clearly and to focus, and also, it can lower the risk of depression.

Coffee and The Added Ingredients

We should be careful about the coffee intake, even if we are healthy but have concerns that we might develop the chronic disease.

The pure form of coffee may be the one that can have a positive effect. But, the coffee drinks with dairy products and added sweeteners do not have the same benefits.

Yes, nowadays the coffee and its consumption are trendy, but drinking coffee on a regular basis is not the best thing to do in order to manage diabetes, even when there is more and more evidence that daily intake of coffee can prevent it.

The café chains usually have sugary, creamy drinks of coffee that have a lot of carbs that are not healthy.

And moreover, these drinks are nothing but calories. The impact that fat and sugar in most of the espresso and coffee drinks can actually outweigh the beneficial and good protective effect of the coffee itself.

It is the same for coffee that is artificially sweetened and sugar-sweetened and other alike drinks.

When there is a sweetener, there are no more benefits that help combat T2D. And what sweetened coffee does is actually increasing the risk of developing the disease.

There can be insulin resistance if we regularly consume coffee drinks that are high in carbs and also in saturated fat. That with time can lead to T2D.

The big coffee chains usually have options with less fat and carbs. These so-called “skinny” coffee drinks are good for any occasion.

Warning and Risks

Bear in mind that even healthy people may experience particular side effects due to the caffeine found in coffee.

Common Side Effects of Coffee:

  • Anxiety
  • Headaches
  • Restlessness

Like with many other things the moderation is crucial. However, even if we drink coffee with moderation, there can still be some risks. That is why we need to consult our doctor.

Warnings and Risks:

  • Increased levels of blood glucose after eating
  • Increase in cholesterol with espresso or unfiltered kinds of coffees
  • Increased risk of gaining weight if we drink coffee with added cream and sweeteners
  • Adolescents on a daily basis should consume less than 100 milligrams of caffeine (all the drinks that have caffeine are included in this daily recommendation)
  • Increased heartburn risk
  • Young children should avoid consuming drinks that have caffeine

Word of Caution

Remember that there is not any supplement and food that act as the protector against developing this chronic disease.

We need to exercise and get fitter in order to lower the risk, in case we have prediabetes.

Drinking coffee does not guarantee that we won’t develop it. We might want to start adding less sugar in our coffee.

It’s always a good idea to consult our doctor about the effects of coffee and what type of exercise and diet we should be having.

Sources: Mayo ClinicHealthline


  • 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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