Does caffeine affect diabetes


10 Surprising Things That Can Spike Your Blood Sugar

When you first found out you had diabetes, you tested your blood sugar often to understand how food, activity, stress, and illness could affect your blood sugar levels. By now, you’ve got it figured out for the most part. But then—bam! Something makes your blood sugar zoom up. You try to adjust it with food or activity or insulin, and it dips really low. You’re on a rollercoaster no one with diabetes wants to ride.

Knowledge is power! Look out for these surprising triggers that can send your blood sugar soaring:

  1. Sunburn—the pain causes stress, and stress increases blood sugar levels.
  2. Artificial sweeteners—more research needs to be done, but some studiesexternal icon show they can raise blood sugar.
  3. Coffee—even without sweetener. Some people’s blood sugar is extra-sensitive to caffeine.
  4. Losing sleep—even just one night of too little sleep can make your body use insulin less efficiently.
  5. Skipping breakfast—going without that morning meal can increase blood sugar after both lunch and dinner.
  6. Time of day—blood sugar can be harder to control the later it gets.
  7. Dawn phenomenon—people have a surge in hormones early in the morning whether they have diabetes or not. For people with diabetes, blood sugar can spike.
  8. Dehydration—less water in your body means a higher blood sugar concentration.
  9. Nose spray—some have chemicals that trigger your liver to make more blood sugar.
  10. Gum disease—it’s both a complication of diabetes and a blood sugar spiker.

Watch out for other triggers that can make your blood sugar fall. For example, extreme heat can cause blood vessels to dilate, which makes insulin absorb more quickly and could lead to low blood sugar. If an activity or food or situation is new, be sure to check your blood sugar levels before and after to see how you respond.

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CDC’s Division of Diabetes Translation
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Ah, that alluring smell of newly brewed coffee can make any coffee drinker yearn for a cup! But have you also noticed that sometimes (or maybe every time), your coffee and diabetes doesn’t seem to agree?

You might see your blood sugar shoot up after that first cup of coffee in the morning or maybe you find that you need extra insulin for your meal when you have a coffee on the side. And maybe that’s making you question; should or can people with diabetes have coffee?

In this post, I will explain everything you need to know about caffeinated beverages: How it impacts blood sugar, its effect on insulin sensitivity, and if coffee is good for people with diabetes.

Table of Contents

How does caffeine work?

We often talk about caffeine and drinks like coffee, RedBull, tea, and Coke as though we simply consume caffeine and suddenly you have energy. The way caffeine boosts your energy is actually much more complex than that!

Blocking adenosine receptors

Adenosine receptors (AR) normally work in your body to actually slow things down. Scientifically speaking, AR binds to your cells and slows down cell activity. This helps you fall asleep at bedtime, for example, or helps your body calm down and recover after intense activity, too.

When you drink caffeine, it actually blocks AR from binding to your cells which enables your cell activity to stay high, giving you more energy and preventing you from falling asleep.

Increasing other energy-producing chemicals

The presence of caffeine also tells your brain to produce more serotonin, dopamine, and acetylcholine.

These are neurotransmitters which essentially help your brain cells communicate. Serotonin, dopamine, and acetylcholine are classified as “neuromodulators” that help regulate your body’s physiological response to activity.

Dopamine and serotonin both have a very positive “rewarding” effect on the brain. An increase in dopamine production, for instance, can occur during a first kiss. It has a pleasing, exciting, giddy-like impact on your brain.

Acetylcholine influences how excited you might feel about something, but it also has a big impact on things unrelated to mood, like muscle function.

Releasing catecholamines

Caffeine also increases your body’s production of catecholamines. Catecholamines are essentially a category of hormones secreted from your adrenal glands. Your adrenal glands will release catecholamines into your bloodstream when you are in a physically or emotionally stressful situation. Those hormones then help your body endure and respond to that stressor.

One of those hormones is adrenaline — and this is exactly why and how caffeine can spike your blood sugar. Let’s take a closer look.

How much caffeine is in coffee, tea, etc.?

The answer to this question is complicated because different sources of coffee, for example, contain different amounts of caffeine. The darker the roast, for example, can significantly change the caffeine content.

A cup of coffee from Starbucks vs. Dunkin’ Donuts will offer vastly different caffeine quantities.

Use this easy “Caffeine Chart” to get a better idea of how much caffeine you’re consuming.

How coffee affects your blood sugar

Okay, so those catecholamines described above include the production of adrenaline (also known as “epinephrine”).

Adrenaline is known as the “flight or fight” hormone. It helps your body endure intense stress — good or bad — like a competition, a rollercoaster ride or a car accident.

Adrenaline helps you endure that stressful event by telling your liver to release stored energy…glucose!

Your liver has stores of glucose, known as glycogen, that it releases at different times every single day. That glycogen is then broken down and converted into glucose to give your body fuel.

During everyday life, your liver is releasing tiny amounts of glycogen between meals to give your brain that second-by-second delivery of glucose it needs in order to function.

During stressful events — like CrossFit or a car accident or a cup of coffee — your liver will release a larger dose of glycogen, giving your body a larger dose of glucose to use for fuel.

And that is how caffeine spikes your blood sugar.

Note: Coffee consumption, especially in the evening, can also decrease sleep quality for some people, which is a known course of decreased insulin sensitivity.

Caffeine and insulin resistance

A study consisting of 10 people with type 2 diabetes set out to determine the impact of regular caffeine consumption on overall insulin levels.

All participants were regular coffee drinkers, consuming about 4 cups of coffee per day, but they all stopped drinking coffee during the study. Then half of them were given capsules containing 250 mg of caffeine, and the other half were given placebo pills containing zero caffeine.

The result, according to the study: “On the days the patients took caffeine, their blood sugar levels were 8% higher. And after every meal — including dinner — their blood sugar spiked higher than it did on the day they had no caffeine.”

Does this mean people with diabetes shouldn’t drink coffee and other caffeinated beverages? Not necessarily. It means we should look closely at our caffeine consumption and moderate it just like we would with other things that impact our blood sugar levels.

Just because black coffee and green tea contain zero calories doesn’t mean we should drink them without limits. Instead, caffeine should ideally be something we consume carefully and set personal limits around for the sake of our overall diabetes health.

Managing your blood sugar around coffee and other caffeinated beverages

In general, you’d have to consume around 200 mg of caffeine to see a blood sugar impact. That’s about 1-2 cups of regular black coffee or 3-4 cups of black tea

However, we are all different and some of us may see a blood sugar impact from just a single cup of coffee while others may be able to drink several cups without any blood sugar changes.

Drinking caffeine at different times of day…

It’s also important to notice whether the time of day you drink caffeine or coffee changes the impact, too.

Most people experience some level of insulin resistance in the morning which wears off throughout the day. Adding coffee to an already insulin resistant situation can be the recipe for very high morning blood sugar. If you also have dawn phenomenon (high morning blood sugars), it might be an idea to convert your morning coffee into you afternoon pick-me-up

What are you adding to your coffee?

Even though those flavored creamers are a mere tablespoon of liquid, they are very high in sugar. Enough sugar to definitely cause an even larger spike in your blood sugar.

One of the most useful things you could do for yourself as a coffee drinker with diabetes is to gradually adjust your tastebuds to appreciate the taste of black coffee.

Try removing the sweetener and milk from your coffee for two weeks. Just two weeks! And see how you start to like the taste of black coffee! You might be surprised to find that you eventually find sweetened coffee to taste overwhelmingly sweet.

Using the spike from coffee to prevent lows…

If you tend to go low during or after exercising, you can use coffee as a way to limit that risk

Drink a cup of coffee about an hour before an intense cardio workout, for example, could prevent low blood sugars without requiring you to eat food, calories, carbs, etc. But remember not all types of exercise drives blood sugar down so you want to combine the coffee with the right type of exercise.

Do you need more insulin for coffee?

To better determine coffee’s impact on your blood sugar, create a simple experiment on a morning when you wake up with an “in-range” blood sugar. Drink a cup of coffee and see where your blood sugar goes during the 1 to 2 hours after that cup of coffee.

Many people simply find they need 1 unit of fast-acting insulin with a cup of coffee.

Or you could test your body’s response to coffee by removing coffee from your morning routine for a few days. Did your insulin needs drop? Were your blood sugars easier to manage? If so, that doesn’t mean you can’t go back to drinking coffee, but it does tell you that you need insulin to help your body deal with the effects of coffee.

It also tells you that limiting your coffee intake is likely a good idea!

You could always switch to decaf!

Caffeine is, of course, an addicting thing. Quitting a coffee habit means enduring pretty intense withdrawal headaches for at least a week or two.

But if you’d like to remove this caffeine variable from your diabetes management, you could always switch to decaf coffee.

There is a little bit of caffeine in decaf coffee but likely not enough to impact your blood sugar.

Either way, it’s all about balance — like everything else in life with diabetes!

Health benefits of drinking coffee

Recent studies have shown that drinking coffee can reduce the risk of developing some serious health conditions and even help you fight depression

  • May protect you from Alzheimer’s disease – a 2002 study found that coffee drinkers have up to a 65% lower risk of Alzheimer’s disease
  • May lower risk of Parkinson’s – studies show that consuming caffeine (not just coffee) significantly lowers the risk of developing Parkinson’s
  • Protects your liver – a 2006 study found that there is an ingredient in coffee that protects against cirrhosis (scarring of the liver caused by many forms of liver diseases and conditions, such as hepatitis and chronic alcoholism)
  • Fights depression – in a 2011 Harvard study, women who drank 4 or more cups of coffee per day had a 20% lower risk of becoming depressed

Side effects of drinking coffee

While coffee is safe to drink for almost everyone, it does have potential side effects that can be more or less severe depending on the individual:

  • Headaches
  • Anxiety
  • Restlessness
  • Sleep problems

For some, regular coffee drinking can also cause digestive issues.

In extremely rare cases, high doses of caffeine can induce psychotic and manic symptoms. People with panic disorder and performance social anxiety disorder should, therefore, be careful when consuming caffeine.

Frequently asked questions

Q: How many cups of coffee can I safely drink per day?

A: There is no absolute standard for this but a general recommendation is to limit caffeine consumption to 400 milligrams per day. That equals about 4 cups of coffee.

If your sleep, mood, or insulin sensitivity is being impacted by the amount of coffee you drink, limiting your intake is advised. It’s also always a good idea to limit or avoid both natural and artificial sweeteners if possible.

Q: Can coffee prevent type 2 diabetes?

A: Even though coffee generally increases insulin resistance (which is thought to be an important factor in developing type 2 diabetes), a 2014 study by researches from Harward who followed more than 100,000 coffee drinkers for 20 years 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.

Also, 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 is not clear why drinking coffee (and not tea) should reduce the risk of developing type 2 diabetes, but the fact that just consuming caffeine did not reduce the risk of developing type 2 diabetes means that it’s most likely something else in coffee that has a positive effect.

Suggested next posts:

  • Gluten and Diabetes: Should People with Diabetes Avoid Gluten?
  • Water and Diabetes – Are You Drinking Enough Water?

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“No sugar! No sweet desserts! No soft drink! No energy drinks!”

Those might be some familiar phrases if you’re diabetic. Cutting out sugar 100% seems to be the best move too.

If you’re diabetic, your first thoughts might be to stop drinking energy drinks, as sugar and caffeine are the biggest ingredients found in many energy drinks.

But wait! I’m not sugar-coating this, but you can still definitely have your favorite energy drinks in some cases.

Disclaimer: you need to be aware of your diabetes condition and what food regulations your doctor might have for you. So, always check with a health professional for the final word before making changes to your diet.

Can diabetics consume caffeine?

Caffeine affects every individual differently, so depending on your diabetic condition, you may or may not be able to consume caffeine.

Diabetics that consume caffeine need to keep an eye on their blood sugar levels.

Healthy adults can consume a recommended maximum daily caffeine intake of up to 400mg. That’s guidance directly from the FDA. However, if you’re diabetic, consume caffeine at lower dosages first and monitor your reaction with each successive dosage increase.

Studies have shown that consuming caffeine in coffee can also lower your risk of type 2 diabetes.

Other research, however has shown that caffeine causes your blood sugar levels to rise. Body mass, age, medications and health condition are all factors that play a role in your blood sugar levels reacting in different ways to caffeine.

I would also like to add, whether you are diabetic or not, if you find yourself reacting negatively to caffeine, then by all means, reduce your intake or cut it out completely.

You can refer to my previous posts, where I wrote about caffeine overdose and caffeine addiction, if you need more information on those topics.

Sugar is unhealthy, regardless of whether you’re diabetic or not.

Can diabetics consume sugar?

Yes diabetics can consume sugar, if they closely monitor their sugar intake.

The recommended maximum daily sugar intake for normal, healthy men is 50g and women is 25g. Of course, diabetics will usually have their own, stricter limitations than these.

It’s wise to not exceed your sugar intake guidelines as it can lead to a spike in your blood sugar levels, which is potentially very dangerous if you’re a diabetic.

While you’re monitoring your sugar intake from beverages, don’t forget that “normal” food items, like rice, bread and biscuits contain varying amounts of sugar too.

Do “sugar-free” products increase blood sugar levels?

If the context of sugar-free here means no sugar or artificial sweeteners present in drinks, then, sugar-free drinks do not increase blood sugar levels.

However, “sugar-free” doesn’t necessarily mean carbohydrate-free or calorie-free, especially if artificial sweeteners are present. Therefore, sugar-free food or beverages aren’t necessarily good for diabetics.

Some artificial sweeteners have carbohydrates or calories and they will likely cause a spike your blood sugar level.

Do artificial sweeteners raise your blood sugar level?

No, artificial sweeteners actually helps to regulate your blood sugar level.

There are two types of artificial sweeteners; nutritive and non-nutritive sweeteners.

The non-nutritive ones are suitable for diabetics, as they have zero calories and won’t increase your blood sugar levels.

Do artificial sweeteners increase insulin levels?

Not directly. Insulin and blood sugar levels work together. However, regular intake of artificial sweeteners can affect your insulin levels to a certain degree.

This occurs when our gut bacteria is unbalanced. Our cells will be resistant to the insulin we produce, thus leading to an increase in blood sugar and insulin levels simultaneously.

Therefore, it is advisable to always consume artificial sweeteners in moderation.

What energy drinks can a diabetic drink?

To make it short and sweet, diabetics can consume caffeine and sugar, in a controlled amount, which allows you to consume many different kinds of energy drinks.


With that said, I would advise you to be on a look out for energy drinks that are strictly zero-sugar, low in calories and with a moderate amount of caffeine.

I personally think you might want to limit your energy drinks intake to possibly only a serving every other day. It is also important to consult your doctor about whether if it is advisable for you to consume energy drinks.

I’ve previously written about drinking energy drinks every single day, but that article isn’t written specifically for diabetics. If you have diabetes you should add an extra layer of caution over what a person without diabetes would need to consider.

Diabetics should NOT consume the original Red Bull due to its high sugar content and calories. But, did you know…Red Bull was once banned

Can a diabetic drink Red Bull?

Yes, a diabetic can drink Red Bull – but they should be the sugar-free or Total Zero versions as opposed to the original version.

The original Red Bull has a whopping 27g of sugar and 110 calories.

Even if you aren’t diabetic it’s probably prudent to avoid drinking that. If you do consume it, make sure to put in extra hours at the gym to burn off those extra calories and maintain an otherwise healthy and balanced diet.

Are zero sugar energy drinks bad for diabetics?

No sugar-free energy drinks are not bad for diabetics. Diabetics can consume zero sugar energy drinks in moderation and with caution.

Zero sugar energy drinks are also more effective at giving you the extra energy that you need without having to worry about a nasty sugar crash afterwards.

What other drinks can diabetics consume?

Water. The best and healthiest drink of all, whether you’re diabetic or not. Water is vital for proper hydration.

Also, there is a possibility that you may mistakenly take your thirst for hunger or sweet cravings. Don’t immediately reach out for a chocolate bar or a box of juice.

Try to drink a glass of water first and then monitor your body’s reaction of the following 15 minutes before binging on some food or other drink. You’ll often find that after 15 minutes you’re not hungry and a glass of water was all you needed.

Now, if you’re like me and don’t really like the idea of plain water, fret not! Choose to infuse your water with berries, cucumbers, mint sprigs or squeeze in pure lemon or lime juice.

Also, another study has proven that adding aloe vera pulp to water is beneficial for diabetics.

Despite containing carbohydrates, milk is healthy and safe for diabetics. But, remember to choose the unsweetened, low-fat, or skim versions of your preferred milk.

Caffeine is safe for consumption by diabetics, and therefore, so is coffee and tea.

However, it’s probably best to have your tea or coffee without any additional sweeteners or creamers.

Energy drinks are often loaded in sugar and caffeine. So, if you’re diabetic, take the time to read the ingredients to choose the best one for you – there are plenty of great sugar-free options out there too.

Best energy drink for diabetics

Ultimately, you should choose an energy drink that has zero sugar, is low in calories that has a sensible amount of caffeine.

I’ve gathered a few top energy drinks to recommend you, but remember to exercise caution and read the ingredients list thoroughly before you choose to add any of these to your diet if you’re diabetic.

Ready-to-drink energy drinks for diabetics

XS Energy Drink

Sugar – zero, good

Caffeine – 80mg, moderate

Calories – 10 per serving, good

I’m on the fence with XS Energy Drink just because of its high price point, with shipping, a single 8.4 fl.oz can costs around $3-$4.


However, I can’t deny that it’s a suitable choice for diabetics. Also, it comes in 18 different flavors for you to choose from, with 2 caffeine-free options if you decide you prefer that.

Also, there are occasionally cheaper deals to be found, so it’s worth checking the prices from time to time anyway.

Check the current price on Amazon.

Xyience Energy Drink

Sugar – zero, how I like it

Caffeine – 176mg, now that’s quite high so please ensure you have a good caffeine tolerance if you decide to go for this energy drink

Calories – zero, a thumbs up from me

Although the zero sugar and calories seems like a good deal, the price point is just too expensive, in my opinion. $4.25 for a can of 16 fl. oz?

No thank you.

Powder energy drink options for diabetics

Powdered energy drinks are a great option to check out too.

Not only are they usually more affordable than most ready-to-drink energy drinks, they are a lot more convenient to take with you anywhere you want and they are also versatile with regard to what you can mix them with.

Check the latest price on Amazon.

Advocare Spark Energy Drink

Sugar – zero, of course

Caffeine – 120mg, a bit higher than what I prefer, but not silly

Calories – 15 per serving, you might need to think twice about this, especially if you’re diabetic

One sachet of Advocare Spark Energy Drink should be mixed with 8 fl.oz of water. Each serving costs around $2.50 with shipping.

I guess you can try this if you need a little bit more caffeine than XS Energy Drink, but I’m not a huge fan of the price compared to the next option I’m about to mention. It also has a few extra calories.

Check the latest price on Amazon.

REIZE Energy Drink

REIZE offers monthly deliveries and one-time purchases to suit your preferences.

Sugar – zero, fantastic

Caffeine – 50mg, perfect

Calories – 11 per serving, nice

Wow, I think we have a winner! I personally love the lower caffeine amount, 50mg of caffeine is a sensible amount that will still provide a nice energy boost without blowing your head off.

Most diabetics probably want to avoid having a really strong energy drink, so this is a good option to get a little extra energy.

The combination of caffeine, taurine, ginseng and B group vitamins all work together to provide a perfect energy boost, with no crash.

Did I mention my favorite part of REIZE Energy Drink? It’s super affordable – only around $1 per drink, including delivery directly to your door – that’s amazing value, especially compared to the other options listed above.

Need I say more? What else is better value for money or better for diabetics than REIZE Energy Drink?

Too good to be true? Try it for yourself and you’ll see what I mean!

Remember to discuss this idea with your doctor before making any dietary changes if you’re a diabetic.

Last Updated on November 16, 2019

Do you find yourself unable to function in the mornings until you’ve had your cup of coffee? Or are you simply an avid fan of your favorite seasonal lattes? Chances are you’re not alone! Americans are drinking more coffee than ever, with an estimated 68% of American adults drinking at least one cup per day in 2018.

As popular as coffee is, it’s not surprising how much debate there is over its health benefits (or risks), including how it affects everything from depression to cancer. One commonly discussed topic is whether coffee is good or bad for someone who has diabetes. Here are the facts.

What exactly is diabetes?

With diabetes, your body is either not producing enough insulin (type 1) or not using it efficiently (type 2). Insulin is a hormone that is normally released by your pancreas to help you take the sugar you eat and move it into your cells where it’s converted into energy.

If you can’t make insulin or your body can’t use it, your cells won’t be able to absorb sugar—and it builds up in your blood instead. This can lead to hallmark symptoms of diabetes like excessive thirst and urination, tiredness, and dizziness. Diabetes can also increase your risk for serious complications like kidney disease, vision loss, nerve damage, and heart disease.

What are the “active ingredients” in coffee?

When you think of coffee and diabetes, you may instinctively think it’s bad for you because of all the sugar it often has. But you may be surprised to find out that coffee itself may not necessarily be harmful for your health! Other components in coffee that can affect your health include antioxidants and caffeine:

  • Antioxidants. Studies have found that coffee has several types of antioxidants, chemicals that can affect your body positively by fighting inflammation and neutralizing damaging atoms known as free radicals that can cause aging and illness.
  • Caffeine. Probably the most well-known component in coffee is caffeine. It’s a natural stimulant (and what may be helping keep you awake at work!), but more importantly for coffee-drinkers with diabetes, caffeine has been known to increase blood pressure and affect insulin sensitivity, or how well your body can respond to insulin.

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How does coffee affect blood sugar?

Unfortunately, research on whether coffee is good or bad for diabetes has offered mixed results, partly because the research was not conducted very rigorously. Some studies have suggested that drinking coffee once in a while can be bad for blood sugar levels by making you more insulin resistant. Other studies, however, have suggested that long-term, daily coffee drinking may cause the opposite effect.

In one such study, adults who drank more than 6 cups of coffee a day were found to have lower risk of diabetes than those who drank only 4 to 6 cups a day. Even those who drank just 1 to 4 cups a day demonstrated a lower risk of diabetes than non-drinkers. The exact reason behind this phenomenon is still unknown, but the main hypothesis is that the caffeine in coffee may have improved insulin sensitivity—which means that cells are better able to absorb sugar and take it out of the blood, lowering blood sugar levels overall.

Despite these research findings, it’s important to mention that they do not confirm that coffee absolutely lowers blood sugar, just that the regular coffee drinkers in the study happened to have a lower risk of diabetes in the long term. The studies also did not clarify how much sugar the coffee contained, or if any sugar was used at all. In addition, many factors can affect your blood sugar levels and risk for getting diabetes, including your daily diet and exercise choices, other medical conditions, and family history of diabetes. Overall, the jury is still out, and increasing your coffee intake as a prevention strategy or cure for diabetes is not recommended.

Is coffee safe if I have diabetes?

Although the evidence on coffee benefits is mixed, as long as you keep an eye on your blood sugar and stick to coffee with less sugar, drinking coffee should be safe. You can treat coffee like any other food, watching how much sugar you add and making sure you limit your caffeine consumption to reasonable amounts. Below are some things to keep in mind.

How much caffeine is too much caffeine?

In general, the FDA has recommended 400 mg of caffeine (roughly 4 to 5 cups of coffee) as the maximum limit a healthy adult should drink a day. If you already have diabetes, however, a lower limit may be beneficial. For some people with diabetes, drinking more than 200 mg of caffeine—or half the amount for a healthy adult—may negatively impact blood sugar.

How much sugar is too much sugar?

For people without diabetes, the World Health Organization (WHO) recommends eating less than 10% of your total calories of sugar. For a 2,000-calorie diet, that would translate to 50 g of total sugar from all sources per day. That’s especially important to remember when you get your coffee to go. An average Starbucks mocha can have 25 grams of sugar alone!

If you have diabetes, you need to work with your doctor to figure out the best limit for you. Determining this limit as a percentage of your total daily calories rather a set amount of sugar may allow you to adjust your intake more easily by how much you eat or how much you weigh.

Lastly, if you have any specific dietary questions or concerns, don’t be shy about talking to your nutritionist or healthcare provider. They’ll be happy you checked in and can give you specific recommendations on what types of foods and drinks are best for your body.

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  • 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 consumptio, 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, published in 2014, showed that those that increased their consumption of coffee experienced an 11% decrease in risk of type 2 diabetes over the next 4 years.

    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.

    How Does Coffee Affect My Diabetes and Can I Still Drink It?

    Diabetes and Coffee: How Does It Affect You?

    There are many conflicting opinions about diabetes and coffee, and how drinking coffee can relate both positively and negatively to diabetes.

    Various studies demonstrate coffee may prevent individuals from developing diabetes, while other studies seem to prove coffee can negatively impact blood glucose levels in those who already have diabetes.

    The Theory Behind Coffee Reducing the Risk of Type 2 Diabetes

    Let’s look first at why some researchers believe drinking coffee can lower the risk of developing diabetes.

    One study of more than 12,000 people aimed to prove that the metabolic effects of coffee may reduce the possibility of diabetes.

    After making adjustments for varying factors including:

    • Body mass index
    • Age
    • Blood pressure
    • Occupational
    • Commuting
    • Smoking
    • Leisure time physical activity
    • Alcohol
    • Tea drinking

    The study found coffee drinking showed positive effects on blood glucose levels.

    In observational studies in people who have not been diagnosed with diabetes, coffee helped with reducing blood sugar and insulin levels – the main risk factors for diabetes.

    Studies show that drinking regular or decaf coffee on a daily basis can lower your risk of developing diabetes by 23 to 50 percent.

    The Theory Behind Coffee Increasing Blood Sugar and Insulin Levels

    Research seems to show in those with preexisting diabetes and those without any diagnosis; coffee can raise blood sugars and affect insulin levels.

    One study demonstrated that a single serving of coffee, containing 100 mg of caffeine, negatively affected blood sugar control in healthy but overweight men.

    Other studies showed that consuming caffeinated coffee impaired blood sugar regulation and insulin sensitivity after meals.

    However, this does not happen with decaf coffee, which suggests that caffeine might be what causes the spike in blood sugar.

    In fact, most of the studies on caffeine and blood sugar look at caffeine directly, not coffee.

    What About Long-Term Coffee Drinking?

    The effects of coffee on blood sugars and insulin levels appear to change depending on whether the person is an occasional or habitual coffee drinker.

    Various studies found that people who are used to drinking coffee do not experience increased blood sugar and insulin levels.

    In other studies, researchers found improvements in the fat cell and liver function.

    One study focused on people who did not regularly drink coffee, or only drank it occasionally. Levels of blood glucose and insulin rose at first, but after only 16 weeks of drinking 5 cups a day their levels settled down.

    How Can Coffee Both Raise and Lower Blood Glucose?

    There is no definitive answer to this question yet, but there are a few scientific theories.

    Firstly, it may be that because caffeine increases adrenalin levels which in turn can raise blood glucose, the studies on people who are not used to drinking coffee might be seeing that effect.

    Over time, the body becomes more tolerant to the effect of caffeine and the in the long term may make use of the antioxidants in coffee which can positively influence blood glucose and insulin, canceling out the adverse effect of the caffeine in your java.

    Coffee has also been shown to reduce the risk of nonalcoholic fatty liver disease and connected to insulin resistance and diabetes.

    So Should You Drink Coffee or Not?

    The evidence seems to show that long-term coffee drinkers are less likely to develop diabetes but also that coffee, especially caffeinated coffee, can raise blood glucose levels and have an impact on insulin sensitivity.

    Confusing, right?

    The thing to remember is that everyone reacts differently to coffee.

    My husband can fall asleep with a cup of freshly brewed caffeinated coffee in his hand while if I drink any after 4 o’clock – I can’t sleep for hours.

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    With anything you consume, it is wise to monitor how coffee and other caffeinated drinks act on your blood glucose levels by testing with strips until you can reliably gauge how they affect you.

    If “full fat” coffee affects you negatively with a significant rise in blood glucose, switch to decaf and see if that helps.

    If you find that decaf also affects you in a major way, it might be wise to save your cups as a treat, in the same way, you would with other foods which have an adverse impact on your sugars.

    Coffee Substitutes

    Coffee substitutes are typically made using caffeine-free chicory and are readily available online and in health food stores.

    Moreover, if you miss the caffeine hit in the morning, try replacing it with a brisk walk or run followed by a short refreshing shower to wake you up in time for work instead of the calorie, carb and caffeine-loaded latte you regularly rely on.

    10 Things That Can Spike Your Blood Sugar

    Here are a number of unexpected triggers that can and will send your blood sugar on a ride:

    1 – Heat

    Extreme heat (in baths, hot tubs or sunburns) can cause blood vessels to dilate, which makes insulin absorb more quickly and could lead to low blood sugar.

    2 – Losing sleep

    Even a single night of little to no sleep can lead to some insulin resistance.

    3 – Coffee

    As a result of the effects of caffeine, some people will encounter high or low blood sugars post coffee. This is because certain people are more sensitive to caffeine.

    4 – Artificial sweeteners

    A few studies currently show that they have the capacity to raise BGs though more research is needed.

    5 – The “Dawn Phenomenon”

    Many people encounter hormone surges early on in the day, whether they have diabetes or not. But for those with T1D, this means blood sugar might spike.

    6 – Nasal sprays

    Certain sprays have chemicals that make the liver release more sugar into the bloodstream, resulting in higher BGs.

    7 – Skipping breakfast

    Try not to go without a morning meal, as that can certainly increase BGs after lunch and dinner.

    8 – Gum disease

    This is a potential cause for higher BGs, as well as a common complication of diabetes.

    9 – Time of day

    It’s important to note that as the day goes on, it can get harder and harder to control blood sugar.

    10 – Dehydration

    Drink up! Less water in the body can easily result in high blood sugar, as the amount of sugar in the body becomes more concentrated.

    Be on guard about other possible variable that might make your blood sugar spike. When encountering new foods or activities, be vigilant about checking your BG levels before and after to see how your body responds.

    Cut out coffee diabetics urged

    Diabetics have been urged to cut out coffee, according to a news article in the Daily Mail. The newspaper reports that an American study has shown that “a daily dose of caffeine raises blood sugar by 8 per cent”. They go on to say that drinking caffeine may undermine the effects of medication and that simply giving up drinks containing caffeine may be a way of lowering blood sugar.

    The researchers used a sensor implanted under the skin of 10 people with type 2 diabetes to measure changes in glucose when the participants took caffeine capsules containing the equivalent of about four cups of brewed coffee a day. The design of this study, the small number of participants and the short timescale all indicate that it is unwise to issue advice based on this research alone. Confirmatory research using randomised designs and larger numbers of patients is needed.

    Where did the story come from?

    Dr James Lane and colleagues from the Duke University Medical Centre, Durham, USA carried out the research. It is not clear from the online version, which was published ahead of print, who funded the study. The study was published online in the peer reviewed medical journal: Diabetes Care.

    What kind of scientific study was this?

    This laboratory study used a crossover design, in which patients acted as their own controls in an unrandomised observation of glucose levels.

    The researchers picked five men and five women (average age 63) from their clinic who were habitual drinkers of brewed coffee. All the participants had been diagnosed with type 2 diabetes at least six months before the study began, and their condition was being managed by a stable regimen of diet, exercise, and oral tablets, but not insulin injections.

    Other than diabetes, they were all free of major medical disorders, were non-smokers, and had not been prescribed other medications known to affect glucose metabolism. They were also mostly overweight or obese with an average body mass index (BMI) of about 32. Blood tests indicated that they managed their diabetes well. The measure of HbA1c was low, an average of 6.4%, suggesting that sugar levels had been well controlled over the past 12 weeks.

    A questionnaire asked the participants to report their usual drink consumption and this was used to calculate their average daily caffeine intake as 520mg per day, with a wide variation in the amount individuals took.

    Glucose concentration was monitored using the continuous glucose monitoring system (CGMS), a device inserted just under the skin of the abdomen. The device gives the average glucose concentration every five minutes throughout the day.

    Following insertion of the device, the participants took 250mg of caffeine in capsules at breakfast and the same again at lunch. The participants all had the same liquid breakfast of 720 cal, and their usual diet at lunch and dinner. They recorded what they ate, their medication and avoided strenuous exercise over the study. Each participant took caffeine capsules for 24 hours and placebo (dummy capsules) for 24 hours. The sensor was removed on the third day.

    What were the results of the study?

    The average 24-hour glucose concentration curves show that caffeine increased average levels of daytime glucose (6am to 10pm) compared to placebo.

    The 0.6mmol/L increase in average glucose level over 24 hours compared to placebo was statistically significant. The average level was 7.4 mmol/l on the placebo days compared to 8.0 mmol/L on the caffeine days.

    The researchers say that average glucose concentrations were also elevated in the three hours following the standardised breakfast (8.7 compared to 8.0 mmol/l), lunch (7.8 compared to 6.8 mmol/l), and dinner (8.6 compared to 6.8 mmol/l) on the days that caffeine was consumed.

    What interpretations did the researchers draw from these results?

    The researchers say that “Caffeine had adverse effects on glucose metabolism, producing higher average daytime glucose concentrations”, and exaggerated glucose responses after meals.

    What does the NHS Knowledge Service make of this study?

    This small study in people living with diabetes, adds to laboratory data that has suggested a similar effect. However, the authors acknowledge that it is uncertain how caffeine affects diabetics. There are also other limitations to the interpretation of this study:

    • Apart from the standardised breakfast drink, the researchers did not control the calorie intake of the volunteers, who may have compensated for a lack of caffeine by eating more.
    • The small number of participants means that differences between the groups may have arisen by chance
    • The authors base their conclusions on changes in glucose concentration after meals. However, their statistical analysis was performed on average readings over 24 hours, or for three hours after meals. It would have been possible to perform further statistical analysis, which took into account the similarities and differences between the groups at the start of the study, but this was not done.
    • There was no “wash-out period” between the active and placebo groups, so it is possible that the lower glucose concentrations on the placebo day could have occurred as a response to caffeine withdrawal. The report does not analyse the data according to whether caffeine or placebo was taken first. Though the groups were balanced in some unexplained way.
    • The authors themselves point out that the reverse pattern is seen overnight, where caffeine appears to reduce blood sugar levels.

    Longer studies with randomised controlled designs, in which participants are followed-up for longer, and ideally with periods between measurements that allow the short-term effects of caffeine to wear off, will help to reveal whether the effect shown here is real and if it applies to all people with type 2 diabetes.

    Sir Muir Gray adds…

    An overdose of almost anything carries risks and the numbers of people in this study are too small to make firm recommendations for all people with diabetes. If in doubt, people with diabetes could try to build an extra 30 minutes of walking a day into their life style; that would compensate for the coffee effect – if it is real, and have its own benefits – if not.

    Analysis by Bazian
    Edited by NHS Website

    Links to the headlines

    Coffee bad for diabetics, study suggests.

    The Guardian, 28 January 2008

    Diabetics urged to cut out the coffee to lower blood sugar levels.

    Daily Mail, 28 January 2008

    Warning to diabetics who drink tea and coffee.

    The Daily Telegraph, 28 January 2008

    Links to the science

    Lane JD, Feinglos MN, Surwit RS.

    Caffeine Increases Ambulatory Glucose and Postprandial Responses in Coffee Drinkers with Type 2 Diabetes.

    Diabetes Care 2007; Oct 31

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