Coffee And Type 2 Diabetes: Is Coffee Safe To Drink For Type 2 Diabetes?

ver 10% of Americans live with type 2 diabetes.  Meanwhile, 75%¹ of people in the United States drink coffee, and 62% do it daily. Since the coffee habit comes with pros and cons, many people with chronic conditions worry about its safety.

A moderate amount of coffee is not harmful to most people.  However, since each person's medical history is different, only a doctor can recommend, limit, or restrict coffee consumption.

Let's take a closer look at coffee and type 2 diabetes and find out whether they are compatible.

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Type 2 diabetes and coffee

Research suggests that drinking coffee can reduce the risk of developing type 2 diabetes. A remarkable study² of over 120,000 Americans showed that increasing coffee consumption by more than one cup a day over four years lowered the risk of developing type 2 diabetes by 11%.

Meanwhile, those who decreased their daily coffee consumption by more than one cup increased their risk of developing type 2 diabetes by 17%.

This means that if you don't have diabetes, coffee may help lower the risks of developing it. However, if you are currently treating type 2 diabetes, caffeine may not always be good for your health.

This was suggested by an interesting study³ published about two decades ago. It was demonstrated that caffeine supplementation decreases insulin sensitivity (how well your cells respond to insulin). As caffeine is the major active substance in coffee, debates about the coffee's effects on insulin activity emerged.

Decaffeinated coffee and type 2 diabetes

Caffeine can stimulate your nervous system and make you feel more awake and energized. That's one of the main causes behind this drink's impressive popularity. 

Decaffeinated coffee contains only a small amount of caffeine, reducing the stimulating effect of coffee but also decreasing its side effects. For decades, only about 8% to 9%⁴ of American coffee fans opted for decaf. In recent years, the number nearly doubled. However, it's still low compared to caffeinated coffee consumption.

Besides caffeine, coffee contains other substances,⁵ including:

Antioxidants (chlorogenic acids)

These antioxidants can reduce blood glucose levels. According to studies,⁶ chlorogenic acid is an insulin activator that has an effect similar to metformin, a medication used to control blood sugar levels in patients with type 2 diabetes.

Vitamin B2

This vitamin helps break down fats, carbohydrates, and proteins. It plays a major role in maintaining the energy supply to your body. In general, vitamin B2 can have an anti-inflammatory effect, which is relevant in diabetes management. Studies⁷ show that taking a vitamin B2 supplement may reduce this oxidative stress and decrease complications.


Magnesium can help people with type 2 diabetes manage their blood sugar levels. People with diabetes often suffer from magnesium deficiency. Studies⁸ suggest that magnesium supplements may help with metabolic control and diabetes prevention.

The beneficial effects of these substances cause some experts to suggest that drinking decaffeinated coffee may be preferable for people with diabetes. This way, they can enjoy the key benefits of the substances mentioned above without increasing caffeine-related insulin resistance.

Caffeine and Type 2 diabetes 

While decaffeinated coffee may seem preferable, the lack of the caffeine energy-producing effect makes it less popular among coffee drinkers.

Is caffeine prohibited for people with type 2 diabetes? It depends on your medical history and symptoms. You need to consult your doctor to determine whether regular coffee can worsen your condition.

Some experts believe that the beneficial effect of other substances in coffee may offset the adverse effects of caffeine. That could make moderate amounts of regular coffee safe for some people with type 2 diabetes.

Today, different studies suggest different things about caffeine and diabetes. Some people with diabetes are more sensitive to caffeine than others. That's why there isn't a clear answer to whether caffeine and type 2 diabetes are compatible.

How much coffee can people with diabetes drink? 

Research⁹ shows that to reduce the risk of developing type 2 diabetes, you need to drink three to four cups of coffee a day. But what if you already have diabetes?

A study¹⁰ conducted by Duke University researchers monitored 10 people with type 2 diabetes. All individuals were coffee drinkers who consumed around four cups a day regularly. However, they stopped drinking coffee for the sake of the experiment.

Each person took a 250-mg caffeine (equivalent to two cups of coffee) pill twice daily. As a result, their blood sugar levels increased by 8% compared to the days when they didn't consume caffeine.

Another study¹¹ suggested that while coffee consumption may cause an acute adverse effect, it could improve glucose metabolism in the long term.

Since more studies need to be done to see how caffeine affects people with type 2 diabetes, it may be reasonable to discuss the amount of coffee you can consume with your doctor.

How does coffee affect blood sugar levels?

Scientists are still trying to figure out how caffeine affects blood sugar levels and insulin sensitivity. One of the theories suggests that caffeine raises epinephrine. This hormone may prevent your cells from processing glucose by inhibiting insulin secretion.

Caffeinated coffee can also indirectly affect your blood sugar levels by causing a lack of sleep. People with type 2 diabetes who don't get sufficient sleep may suffer from lower insulin sensitivity. Even if a person is sleep-deprived for just one night, they may experience higher insulin resistance.  

Risks of coffee for people with diabetes 

While drinking moderate amounts of coffee may be beneficial for some people with diabetes, it's important to keep the following risks in mind:

Added ingredients 

All the above studies involved people who drink black coffee. However, only about 35%¹² of American coffee drinkers prefer that type. The rest adds a variety of ingredients that include sugar, artificial sweeteners, milk, and more.

While some of these additives, such as cinnamon, which has many antioxidants, may positively affect blood sugar levels, others do the opposite.

Artificial sweeteners

Studies¹³ show that people who use artificial sweeteners have higher insulin resistance than those who don't.


Milk can cause your blood sugar levels to spike. While small portions of milk may not have adverse effects, too many could make a difference in your glucose levels and increase insulin resistance.


Many people prefer adding flavored syrups to their coffee. These additives contain high amounts of sugar.


Even a small amount of sugar in your coffee can affect your blood sugar levels.

People who live with diabetes need to be careful about the ingredients they add to their coffee. Besides raising glucose levels, certain additives, like butter in bulletproof coffee, may raise cholesterol levels or cause allergies.

Side effects

After experiencing a short-term energy boost, people who drink coffee may also face unpleasant side effects. They include:

For people with diabetes, these symptoms may be related to their condition. For example, those people often suffer from Gastroesophageal Reflux Disease or GERD. Drinking coffee can worsen the symptoms.

Drinking coffee can cause people with diabetes to confuse these symptoms with hypoglycemia (low blood sugar) or hyperglycemia (high blood sugar). This could cause them to take unnecessary measures.

Sleep problems

One of the main reasons some people drink coffee is to stay awake. Meanwhile, one of the side effects of caffeine consumption is insomnia. People with diabetes often suffer from sleep disorders. Drinking coffee could worsen their existing issues.

According to studies,¹⁴ people who suffer from insomnia are 28% more likely to develop type 2 diabetes than those who sleep well. If your diabetes is in remission, it's important to monitor your condition after drinking coffee to avoid sleep problems.

Higher cholesterol

Some studies¹⁵ show that drinking coffee may increase cholesterol levels. Diabetes can damage the lining of your arteries. This makes it easier for cholesterol to stick and increases your chances of developing cardiovascular problems.

It's worth noting that the effect on cholesterol levels depends on the type of coffee you drink. For example, instant coffee doesn't raise cholesterol as much as espresso.

Benefits of coffee for diabetics 

On the other hand, moderate coffee consumption may promote some positive health effects that people with type 2 diabetes may also experience.

Weight loss

Polyphenols and minerals in coffee could improve the effectiveness of insulin and glucose management. This could boost the glucose to energy conversion in people with type 2 diabetes and help them lose weight.

One cup of black coffee has about five calories. Drinking it doesn't contribute to weight gain. Meanwhile, a study¹⁶ shows that one cup of coffee (100 mg of caffeine) can increase your energy expenditure by 8% – 11%.

Lower risk of heart disease

Studies¹⁷ show that drinking two to three cups of coffee a day can reduce your risk of heart disease.

People with diabetes are at a higher risk of developing cardiovascular (heart and blood vessel) disorders. If you don't keep blood glucose levels under control, it can damage blood vessels and nerves that control your cardiovascular system. With time, this could cause heart disease.

Since coffee can reduce your risk of developing heart disease, moderate consumption of this beverage could be beneficial.

Better mood

Coffee contains naturally occurring polyphenols that act as antioxidants and reduce oxidative stress. For some people, this could have a positive neurological effect. It also works as an antidepressant by elevating serotonin and dopamine levels.

People who have diabetes are twice as likely to suffer from depression as those who don't. While coffee can't treat depression, studies¹⁸ show that coffee consumption could reduce the risk of suicide by 50%.

Liver protection 

Both caffeinated and decaffeinated coffee is good for your liver. According to a large British study,¹⁹ coffee may:

  • Prevent liver cancer

  • Lower the risk of liver conditions, such as fibrosis

  • Slow the progression of liver disease

Diabetes is a risk factor for developing chronic liver disease. That's why drinking coffee can benefit people with type 2 diabetes. 

To drink or not to drink?

When diagnosed with diabetes, many people who have a coffee habit start worrying about it. Some stop drinking coffee immediately, while others try to switch to decaf.

Many studies have investigated the impact coffee has on the health of people with type 2 diabetes. None of them is the last word. The decision to drink or not to drink coffee with type 2 diabetes should depend on numerous factors, including:

Since coffee can have many beneficial effects on your health, it may be a good decision to continue moderate consumption. However, it's imperative to speak to your doctor about it.

The lowdown

More studies need to be done to evaluate the effects of coffee on people with type 2 diabetes. Some people with diabetes may benefit from moderate consumption, while others could experience side effects.

It's important to talk to your doctor about your coffee habit. If it's not causing such side effects as heartburn, insomnia, and anxiety, you may not have to reduce the consumption. However, if you notice any unfavorable reactions and blood sugar spikes, you may need to rethink your coffee drinking routine. 

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