Does Black Coffee Affect Blood Sugar?

Medically Reviewed By: DR. Rashmi GR, M.B.B.S, Diabetologist January 6, 2022

Last updated on April 18th, 2022

Coffee was once destined as being harmful for a person’s health. But an increasing number of evidences state that coffee helps in guarding several forms of cancers, liver problems, and even depression. In addition, there is convincing research suggesting that when the coffee consumption is increased, the risk of developing diabetes type 2 reduces. This is good news for people who can’t face the day until they enter their cup of java. On the other hand, for people who already suffer from type 2 diabetes, coffee could exert certain adverse effects. Whether a person is trying to lower his or her risk, he or she already has diabetes; keep on reading to learn about the effects of black coffee on diabetes.

Does black coffee affect blood sugar?

Caffeine might reduce a person’s insulin sensitivity. That implies that the body cells fail to respond to the hormone by as much as they once did. They fail to absorb as much glucose from the bloodstream after a person consumes or drinks. This makes a person’s body to produce a large amount of insulin, hence the levels become higher after meals. If a person has type 2 diabetes, his or her body already doesn’t make use of insulin appropriately. After meals, the blood glucose elevates higher than the standard limits. Caffeine might make it harder to bring it down to a healthy range. This might give rise to too-high blood glucose levels. With time, this might increase the chance of diabetes complications, such as cardiovascular problems or nerve damage.

What is Diabetes?

Diabetes is a medical condition that has an impact on how a person’s body processes blood sugar. Blood sugar is vital as it’s what fuels a person’s brain and provides energy to his or her tissues and muscles. If a person is diabetic, that implies that he or she has an excess of glucose circulating in the blood. This happens when an individual’s body becomes insulin resistant and fails to effectively uptake glucose into the body cells for fuel. Too much sugar in the blood might cause severe health concerns. There are several different factors responsible for diabetes.

Types of chronic diabetes include type 1 and type 2. Other types may be gestational diabetes, which happens during pregnancy however, fades away after birth. Prediabetes, at times known as borderline diabetes, implies that a person’s blood sugar levels are greater than normal but not so high that a person would be diagnosed with diabetes.

Few signs of diabetes can be weakness, enhanced thirst, irritation, and unexplained weight loss. If a person thinks he or she may experience few of these signs, it’s a must to discuss with a doctor.

Also Read: Symptoms of Type 1 Diabetes in Toddlers

Coffee and Possible Prevention of Diabetes

The health advantages of black coffee for diabetes varies from person to person. It was found that individuals who increased their coffee consumption by above 1 cup each day had an 11% reduced risk of developing diabetes type 2. On the other hand, individuals who lowered their coffee consumption by 1 cup each day enhanced their risk of developing diabetes by 17%. There was no variance in people having tea. It’s not evident why black coffee has such an influence on the progression of diabetes.

Thinking caffeine? It might not be accountable for those good benefits. In actual fact, caffeine has been found to enhance both insulin and sugar levels in the short term. In a research study involving males, decaffeinated coffee presented a short-term rise in blood glucose level. There are limited studies and more research requires to be performed on the effects of diabetes and caffeine.

Also Read: Top 10 Early Signs and Symptoms of Diabetes in Men & Women

Why Caffeine Exerts These Effects?

Studies think caffeine affects a person’s insulin and blood glucose levels in the following ways:

  • Caffeine increases the levels of various stress hormones, such as epinephrine (or, adrenaline). Epinephrine helps in preventing the body cells from processing as much glucose. Also, it might keep a person’s body from producing as much insulin.
  • It inhibits a protein named adenosine. This protein plays a huge role in how much insulin a person’s body produces. Moreover, it helps in regulating how the body cells react to it. Caffeine keeps adenosine which is responsible for producing insulin in a person’s body.
  • It takes a toll on the sleep patterns. An excess of caffeine keeps a person awake. Lack of sleep might reduce his or her insulin sensitivity.

The Effect of Black Coffee on Insulin and Glucose

While coffee seems to be beneficial for guarding individuals against diabetes, few research studies have found that a plain black coffee might pose dangers to individuals who already experience diabetes type 2.

Also Read: Normal Sugar Level After Meal

Caffeine, Blood Sugar, and Insulin (Pre & Post-meal)

One research study exhibited that consumption of a caffeine capsule prior to consuming food resulted in greater levels of post-meal sugar in type 2 diabetic patients. It also demonstrated an upsurge in insulin resistance. As per a recent research study, a genetic supporter might be involved. Genes might play a key role in the metabolism of caffeine and how it influences blood glucose. In this study, people who metabolized caffeine at a slow speed depicted greater blood glucose levels in comparison to people who genetically metabolized caffeine at a fast rate.

Diabetes and Black Coffee

Certainly, there’s a lot more in coffee excluding caffeine. These other things might be what’s accountable for the defensive effect seen in the research study. Intake of caffeinated coffee over a long-time duration might also alter its effect on insulin and glucose sensitivity. Tolerance from chronic intake might be what causes the defensive effect. Another study demonstrated that chronic effects of coffee and caffeine might be associated with reduced risk of prediabetes as well as diabetes.

Fasting Blood Sugar and Insulin

Another study explored at a “mid-range” effect on individuals without diabetes who had been either consuming one litre of regular paper-filtered coffee per day, or who had withdrawn. At the end of the 4-week study, people who took more coffee had greater quantities of insulin in their blood. This was the situation even while fasting. If a person is type 2 diabetic patients, his or her body is incapable of utilizing insulin efficiently to manage blood glucose level. The “tolerance” effect seen in chronic black coffee intake takes a lot longer than 4 weeks to progress.

Also Read: Can diabetics eat mango?

Typical Intake of Black Coffee

There’s a clear variance in how diabetic people and non-diabetic people react to coffee and caffeine. A recent study consumed typical coffee drinkers with type 2 diabetes constantly monitor their blood glucose while performing every day activities. Throughout the day, it was found that right after they consumed black coffee, their level of blood glucose would ascend. Blood glucose was seen to be greater on days that they took coffee as compared to on days they didn’t.

Other Health Benefits of Coffee

Various other benefits of intake of black coffee that aren’t associated with prevention of diabetes. Newer studies with measured risk factors have been showing other benefits of coffee. They involve potential defense against:

  • Alzheimer’s disease
  • Parkinson’s disease
  • liver disorder such as liver cancer
  • gallstones
  • gout

These recent studies have also found that black coffee appears to reduce the risk of depression as well as enhance the capacity of focussing and thinking clearly.

Coffee with Added Constituents

If a person is non-diabetic, however is worried about developing it, watch out before enhancing the consumption of black coffee. There might be a positive effect from black coffee in its pure form. On the other hand, the benefits aren’t similar for coffee beverages with additional sweeteners or dairy products.

Daily Diabetes Tip

Coffee might be more prevalent than ever, but consuming it regularly isn’t the finest way to manage diabetes, even though there’s increasing evidence that it could aid in diabetes management. Creamy, sugary beverages found at cafe chains are repeatedly packed with unnatural carbohydrates. In addition, they are rich in calories.

The impact of the fat and glucose in loads of black coffee and espresso beverages might balance the good from any defensive effects of the black coffee. The same can be said in relation to glucose-sweetened as well as even artificially syrupy coffee or other drinks. Once sweetener is included, it enhances the risk of developing diabetes type 2. Intake of too many extra sugars is directly associated with obesity and diabetes.

Intake of black coffee beverages rich in saturated fat or sugar often may augment insulin resistance. It might also add to type 2 diabetes. Many big coffee chains offer drink alternatives containing a smaller number of carbohydrates and fat. “Skinny” coffee beverages let a person the morning wake-up or afternoon refreshment deprived of the sugar rush.

Few healthy tips to flavour black coffee such as:

  • include cinnamon and vanilla as a healthy, zero carb alternative
  • opt for an unsweetened vanilla milk alternative including flax, coconut, or almond milk
  • demand ½ the quantity of flavoured syrup while ordering from coffee shops, or forbidding syrup in total

Also Read: Diabetes and Heart Diseases: Know How Does Diabetes Affect the Heart

Risks and Warnings

Even for healthy people, the caffeine content in the black coffee might exert few side effects. The common ill effects of caffeine are headache, nervousness, and agitation. As with most everything, self-control is very important in the intake of black coffee. On the other hand, regardless of moderate intake, coffee does have risks that a person must speak to a doctor.

These risks include:

  • an enhanced cholesterol with unfiltered or espresso form of coffee
  • an enhanced risk of heartburn
  • augmented levels of blood sugar following a meal

Other things to retain:

  • Adolescents must consume below 100 mg of caffeine on a daily basis. This involves all caffeinated beverages, not just coffee.
  • Young kids must not consume caffeinated drinks.
  • Adding an excess of sweetener or cream might enhance the risk of diabetes and obesity as well.


No food or supplement delivers total defense against diabetes type 2. If a person is prediabetic or is at risk for getting diabetes, exercising, losing weight, as well as taking a balanced, nutrient-rich diet is the excellent approach of lowering a person’s risk. Taking up drinking coffee so as to ward off diabetes won’t promise an effective result. But if a person is already having black coffee, it might not hurt. Try lowering down the quantity of sugar or fat a person drinks with coffee. Also discuss with a healthcare provider regarding diet options, exercise, as well as the effects that coffee intake may have.


Is it good to have black coffee one hour before the glucose test?

Avoid having or drinking anything except water for at least 8 hours prior to the test. Plain water is suggested only. Avoid having tea, coffee, soda (regular or diet) or any other drinks.

Does black coffee have an effect on the blood test results?

Although, a person consumes it black, coffee has been found to hinder with blood test results. That’s due to the reason that it consists of caffeine as well as soluble plant matter, which may twist the test results. In addition, coffee is a diuretic, which implies that it would enhance the amount of urine. Also, this might have a dehydrating effect.

Does black coffee elevate blood glucose level?

For many young, healthy adults, caffeine doesn’t seem to markedly impact the level of blood glucose, and consuming up to 400 mg each day seems to be safe.

Does coffee elevate blood glucose in a fasting state?

Morning brew has been found to impair blood glucose response by 50% when taken on empty stomach.



Last Updated on by Dr. Damanjit Duggal 


The information included at this site is for educational purposes only and is not intended to be a substitute for medical treatment by a healthcare professional. Because of unique individual needs, the reader should consult their physician to determine the appropriateness of the information for the reader’s situation.

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