Coffee was once condemned as being bad for your health. Yet, there’s growing evidence that it may protect against certain kinds of cancers, liver disease, and even depression.

There’s also compelling research to suggest that increasing your coffee intake may actually lower your risk for developing type 2 diabetes. This is good news for those of us who can’t face the day until we get in our cup of java.

However, for those who already have type 2 diabetes, coffee could have adverse effects.

Whether you’re trying to lower your risk, you already have diabetes, or you just can’t go without your cup of joe, learn about coffee’s effects on diabetes.

Diabetes is a disease that affects how your body processes blood glucose. Blood glucose, also known as blood sugar, is important because it’s what fuels your brain and gives energy to your muscles and tissues.

If you have diabetes, that means that you have too much glucose circulating in your blood. This happens when your body becomes insulin resistant and is no longer able to efficiently uptake glucose into the cells for energy.

Excess glucose in the blood can cause serious health concerns. There are a number of different factors that can cause diabetes.

Chronic diabetes types are type 1 and type 2. Other types include gestational diabetes, which occurs during pregnancy but tends to go away after birth.

Prediabetes, sometimes called borderline diabetes, means your blood glucose levels are higher than usual but not so high you would be diagnosed with diabetes.

Some signs and symptoms of diabetes include:

If you think you might have some of these symptoms, it’s important to talk to your doctor.

The health benefits of coffee for diabetes differs from case to case.

Researchers at Harvard tracked over 100,000 people for about 20 years. They concentrated on a four-year period, and their conclusions were later published in this 2014 study.

They found that people who increased their coffee intake by over one cup per day had an 11 percent lower risk of developing type 2 diabetes.

However, people who reduced their coffee intake by one cup per day increased their risk of developing diabetes by 17 percent. There was no difference in those drinking tea.

It’s not clear why coffee has such an impact on the development of diabetes.

Thinking caffeine? It may not be responsible for those good benefits. In fact, caffeine has been shown in the short term to increase both glucose and insulin levels.

In one small study involving men, decaffeinated coffee even showed an acute rise in blood sugar. Right now there are limited studies and more research needs to be done on the effects of caffeine and diabetes.

While coffee could be beneficial for protecting people against diabetes, some studies have shown that your plain black coffee may pose dangers to people who already have type 2 diabetes.

Caffeine, blood glucose, and insulin (pre- and post-meal)

One 2004 study showed that taking a caffeine capsule before eating resulted in higher post-meal blood glucose in people with type 2 diabetes. It also showed an increase in insulin resistance.

According to a recent 2018 study, there may be a genetic proponent involved. Genes may play a role in caffeine metabolism and how it affects blood sugar. In this study, people who metabolized caffeine slower showed higher blood sugar levels than those who genetically metabolized caffeine quicker.

Of course, there’s a lot more in coffee other than caffeine. These other things may be what’s responsible for the protective effect seen in the 2014 study.

Drinking caffeinated coffee over a long period of time may also change its effect on glucose and insulin sensitivity. Tolerance from long-term consumption may be what causes the protective effect.

A more recent study from 2018 showed that long-term effects of coffee and caffeine may be linked to lowering risk of prediabetes and diabetes.

Fasting blood glucose and insulin

Another study in 2004 looked at a “mid-range” effect on people without diabetes who had been either drinking 1 liter of regular paper-filtered coffee a day, or who had abstained.

At the end of the four-week study, those who consumed more coffee had higher amounts of insulin in their blood. This was the case even when fasting.

If you have type 2 diabetes, your body is unable to use insulin effectively to manage blood sugar. The “tolerance” effect seen in long-term coffee consumption takes a lot longer than four weeks to develop.

Habitual coffee drinking

There’s a clear difference in how people with diabetes and people without diabetes respond to coffee and caffeine. A 2008 study had habitual coffee drinkers with type 2 diabetes continuously monitor their blood sugar while doing daily activities.

During the day, it was shown that right after they drank coffee, their blood sugar would soar. Blood sugar was higher on days that they drank coffee than it was on days they didn’t.

There are other health benefits of drinking coffee that aren’t related to diabetes prevention.

Newer studies with controlled risk factors have been showing coffee’s other benefits. They include potential protection against:

These newer studies have also shown that coffee seems to decrease depression risk and increase ability to focus and think clearly.

If you don’t have diabetes but are concerned about developing it, be careful before increasing your coffee intake. There may be a positive effect from coffee in its pure form. However, the benefits aren’t the same for coffee drinks with added sweeteners or dairy products.

Daily diabetes tip

  • Coffee may be more popular than ever, but drinking it on a regular basis isn’t the best way to manage diabetes — even if (believe it or not) there’s growing evidence that it could help prevent diabetes.

Creamy, sugary drinks found at cafe chains are often loaded with unhealthy carbs. They’re also very high in calories.

The impact of the sugar and fat in a lot of coffee and espresso drinks can outweigh the good from any protective effects of the coffee.

The same can be said about sugar-sweetened and even artificially sweetened coffee and other beverages. Once sweetener is added, it increases your risk of developing type 2 diabetes. Consuming too many added sugars is directly linked to diabetes and obesity.

Having coffee drinks that are high in saturated fat or sugar on a regular basis can add to insulin resistance. It can eventually contribute to type 2 diabetes.

Most big coffee chains offer drink options with fewer carbs and fat. “Skinny” coffee drinks allow you the morning wake-up or afternoon pick-me-up without the sugar rush.

Some healthy tips to flavor your coffee include:

  • add vanilla and cinnamon as a healthy, zero carb option
  • choose an unsweetened vanilla milk option, such as coconut, flax, or almond milk
  • ask for half the amount of flavored syrup when ordering from coffee shops, or nixing syrup altogether

Even for healthy individuals, the caffeine in coffee can have some side effects.

Caffeine’s common side effects include:

As with most everything, moderation is the key in coffee consumption. However, even with moderate consumption, coffee does have risks that you should discuss with your doctor.

These risks include:

Other things to keep in mind:

  • Adolescents should have less than 100 milligrams (mg) of caffeine each day. This includes all caffeinated drinks, not just coffee.
  • Young children should avoid caffeinated drinks.
  • Adding too much sweetener or cream can increase your risk of diabetes and becoming overweight.

No food or supplement offers total protection against type 2 diabetes. If you have prediabetes or are at risk for getting diabetes, losing weight, exercising, and consuming a balanced, nutrient-dense diet is the best way to reduce your risk.

Taking up drinking coffee in order to stave off diabetes won’t guarantee you a good result. But if you already drink coffee, it may not hurt.

Try reducing the amount of sugar or fat you drink with your coffee. Also talk with your doctor about diet options, exercise, and the effects that drinking coffee might have.

Q:

I have type 2 diabetes. How many cups of coffee can I have a day?

A:

This is dependent on the person, as there’s no one-size-fits-all recommendation. However, in general, having unsweetened coffee in moderation is okay for those with type 2 diabetes. The typical recommendation is to not have more than 400 milligrams of caffeine per day. This equals about 4 cups of coffee.

If your mood, sleep, blood sugar, and energy are being affected, limiting intake may be advised. The most important thing when choosing coffee for people with diabetes or those managing their weight is to pay attention to the carbohydrate content from milk and added sweeteners. Cutting back or eliminating artificial sweeteners is advised as these have shown to disrupt gut bacteria, cause cravings and overeating, and negatively impact weight and blood sugar management.

Traditional lattes, cappuccinos, and flat whites all contain milk, and may have added sweeteners if you get a flavor. Caffeinated drinks that have no carbohydrates include Americanos, espressos, and just black coffee. Whether you prefer coffee beans or instant coffee powder doesn’t make a difference nutritionally, however taste, freshness, and caffeine content may vary.

Instead, opt for using honey as a sweetener, and pair with an unsweetened milk option over creamer. This will decrease saturated fat and carbohydrate intake while still providing flavor. Stick to 1 tablespoon of honey or less, which contains 15 grams of carbohydrates. Traditional coffee drinks can contain up to 75 grams of carbohydrates from added sugar, so this cuts it down significantly.

Natalie Olsen, RD, LD, ACSM EP-C Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.