Can black coffee raise your blood sugar

The effect of coffee on diabetes, when presented in the media can often be confusing.

News stories can in the same week tout the benefits coffee can have on diabetes and shoot down coffee as being unhelpful for blood sugar levels.

This doesn’t mean the articles are contradictory though.

Put slightly more simply, coffee contains different chemicals, some of which have beneficial effects whereas others can have a less beneficial effect, such as caffeine which can impair insulin in the short term.

Caffeine and blood sugar levels

Regular high caffeine consumption, over a 4 week period, has been shown to impair insulin sensitivity in people with type 2 diabetes.

Whilst the researchers found a relationship between higher coffee consumption and lower sensitivity to insulin, they recognised that the rapid transition to having more coffee may have produced an atypical or emphasised response by the body.

Benefits of coffee

Coffee has been shown to lower risks of the following conditions:

  • Type 2 diabetes
  • Cancer – such as endometrial cancer and aggressive prostate cancer
  • Cardiovascular disease
  • Strokes
  • Alzheimer’s disease
  • Parkinson’s disease

Coffee contains polyphenols, which are a molecule that anti-oxidant properties which are widely believed to help prevent inflammatory illnesses, such as type 2 diabetes, and anticarcinogenic (anti-cancer) properties.

As well as polyphenols, coffee contains the mineral magnesium and chromium. Greater magnesium intake has been linked with lower rates of type 2 diabetes.

The blend of these nutrients can be helpful for improving insulin sensitivity, which may help to offset the opposite effects of caffeine.

Coffee and prevention of diabetes

Coffee and its effect on risks of developing type 2 diabetes have been studied a number of times and has indicated a notably lower risk of type 2 diabetes being associated with coffee drinkers.

A 2009 study of 40,000 participants noted that consumption of 3 cups of tea or coffee a day lead to a 40% lower risk of type 2 diabetes developing. A study of healthcare professionals in the US and UK, five years later, showed that those thatincreased their consumption of coffee experienced an 11% decrease in risk of type 2 diabetes over the next 4 years.

More recently, research found in 2022 that drinking two coffees a day reduces risks of cardiovascular disease and early death and that it may may reduce the risk of developing Alzheimer’s disease.

In addition, drinking coffee has been shown to boost physical activity levels.

Decaffeinated coffee and blood glucose

So whilst caffeine may hamper insulin sensitivity, other properties in coffee have the opposite effect.

It is therefore believed that decaffeinated coffee may present the best option for people with diabetes as researchers find it includes the benefits of coffee with some of negative effects that are associated with caffeine.

Lattes and syrups in coffee

Some varieties of coffee need to be approached with caution by those of us with diabetes. Coffees with syrup have become a much more popular variety of coffee within the 21st Century but could be problematic for people either with or at risk of, diabetes.

If you have diabetes or are at risk of diabetes, it is advisable to reduce your exposure to too much sugar. If you wish to enjoy a syrupy coffee from time to time, pick the smaller sized cups and drink slowly to better appreciate the taste without dramatically raising your blood glucose levels.

Another modern trend in coffee is in the popularity of lattes, very milky coffees. Lattes present two considerations: the number of calories in the latte and the amount of carbohydrate in them.

Whilst skinny lattes are usually made with skimmed milk, some of them may be sweetened which will raise their calories. Milk, whether full fat or skimmed, tends to have around 5g of carbs per 100g. A regular, unsweetened skinny latte can typically contain anywhere between 10 and 15g of carbohydrate.

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:

  • increased thirst
  • unexplained weight loss
  • fatigue
  • irritability

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:

  • Parkinson’s disease
  • liver disease, including liver cancer
  • gout
  • Alzheimer’s disease
  • gallstones

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.

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.

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

Caffeine’s common side effects include:

  • headaches
  • restlessness
  • anxiety

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:

  • an increase in cholesterol with unfiltered or espresso-type coffees
  • an increased risk of heartburn
  • elevated blood glucose levels after a meal

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.