Coffee and Blood Sugars: What’s the Connection?

If you’re a coffee drinker and live with diabetes, you may be familiar with the difficulty that drinking a regular morning cup of joe can be. Coffee is one of the most popular drinks on the planet, with the average U.S. adult drinking two 8 oz cups of coffee per day.

Whether you spike or crash, drinking and enjoying coffee is made infinitely harder when living with diabetes. So, what’s the deal? What exactly does coffee do to your blood sugars, and how can you help mitigate the damage?

This article will outline the effects that coffee has on blood sugar levels and ways you can prepare and guard against any negative side effects from your morning routine.

What Is It About Coffee That Affects Blood Sugar?

The majority of people with diabetes see a spike in their blood sugar when drinking coffee, and it’s not a mystery that a lot of the cause can be attributed to the caffeine content in your morning cup.

According to the Mayo Clinic, for people with diabetes, about 200 milligrams of caffeine (about one to two 8 oz cups of plain, brewed coffee) can cause a spike. Caffeine causes insulin resistance and can negatively affect postprandial blood sugar levels, essentially requiring you to take more insulin for foods eaten when you drink caffeinated beverages. Some people even need to bolus for drinking plain, unsweetened, black coffee that has no carbohydrates.

Ironically, long-term coffee consumption is associated with higher insulin sensitivity and lower rates of type 2 diabetes, but in the short term, the caffeine content causes a spike in blood sugars and lower insulin sensitivity. Caffeine is also an appetite suppressant, so its overall effect is sometimes balanced out.

The best option for people with diabetes who are struggling with blood sugar spikes post cup, however, may be to opt for decaf: drinking decaffeinated coffee seems to curb blood sugar spikes in individuals.

Why Does Caffeine Cause Blood Sugar Spikes?

Caffeine spikes blood sugars in a number of ways, including:

  • Naturally raising levels of certain stress hormones, epinephrine, and adrenaline, making you more insulin resistant when you drink it
  • Blocking the protein adenosine, tamping down the amount of insulin your body produces (if you’re type 2), making it more difficult for the body to process carbohydrates as quickly, spiking your blood sugar levels.
  • Inhibiting sleep, when consumed later on in the day. Lack of sleep for even a few days has proven to lower insulin sensitivity and increase insulin resistance, keeping blood sugars stubbornly high

And it isn’t only the caffeine found in coffee affecting blood sugars. A 2004 study showed that taking a caffeine pill before eating resulted in higher post-meal blood sugars and insulin resistance for people with type 2 diabetes. The same can be inferred for caffeinated sodas, chocolate, tea, energy drinks, and even protein bars.

Other Factors That Contribute to Higher Blood Sugars

The caffeine content in coffee is not the only thing to blame for higher blood sugar levels, however. Many people prefer coffee first thing in the morning, right when they’re often already experiencing the higher blood sugars associated with the dawn phenomenon, and combining the two can make it harder to get levels back under control.

Frappucino: sugar-loaded coffee

Photo credit: iStock

Additionally, beware of added sugars, syrups, and sweetened-dairy products that can quickly add empty calories (and carbohydrates!) to your morning brew. The difference in carbohydrate counts between one cup of black coffee (1 gram) and a Grande Frappuccino from Starbucks (50 grams) is stark and can make all the difference between a “good” blood sugar day and a difficult one. Having coffee beverages that are high in saturated fat and sugar on a regular basis can contribute to both insulin resistance and the development of type 2 diabetes.

Even an innocuous latte can still have anywhere between 12-25 grams of carbohydrates, simply from the sugars found in milk.

Ways to Combat the ‘Coffee Spike’

There are many ways to help combat the blood sugar spike from coffee, including:

  • Try not drinking coffee first thing; go for a 20-minute walk to combat the dawn phenomenon before you imbibe
  • Switch to decaf, or even half-caf
  • Cut down on your overall consumption (one to two 8oz cups of brewed coffee per day is plenty)
  • Do not drink coffee late in the day (try to drink it before noon), so it does not negatively affect your sleep, and thus insulin resistance
  • Drink only black coffee, cold brew coffee, or coffee with a touch of (unsweetened) dairy or non-dairy milk, cream, or half-and-half
  • Do not add syrups or sugar to your coffee; opt for stevia instead
  • Add vanilla extract, cinnamon, or sugar-free syrups to your coffee for extra taste
  • If you regularly spike, even from black coffee, aim to pre-bolus before a cup, taking a dose for your coffee 10-15 minutes before drinking
  • Get some morning exercise in immediately after drinking a cup to help curb the spike
  • Talk with your doctor about additional strategies to incorporate coffee into a healthy diet

The routine of a morning cup of coffee is essential to millions of people around the world, but a blood sugar spike is never enjoyable. Incorporating some of these strategies can help you mitigate the negative effects on blood sugar, while still allowing you to enjoy what you love! A little planning and preparation can make all the difference. And that’s definitely something to celebrate. Cheers!


Why Your Breakfast Matters

People say that breakfast is the most important meal of the day. Then again, you probably get confused because you hear about people who don’t eat breakfast and do intermittent fasting… and they seem like they’re doing perfectly fine.

So, who do you believe? What do you do? What’s the best thing for you? And most importantly, what’s the best thing for your blood sugars?

At the end of the day, we want to make sure our blood sugar levels are in the best possible place, and breakfast, should you choose to eat it, does play a massive role in that, as it sets the tone for the entire day. So, let’s make sure you’re crushing it at breakfast.

Here are three important considerations that you need to be thinking about when it comes to eating breakfast:

1. Insulin Resistance in the Morning

You might have noticed over time that no matter what you do, you eat something for breakfast that has plenty of carbs in it, and your blood sugar skyrockets. You could be eating cereal, you could be eating some toast–no matter what you eat, your blood sugar just goes to the moon, and it is super frustrating. “Why?” you wonder. “This makes no sense.”

However, here’s the situation: Your body produces a hormone called cortisol, which is not the friendliest hormone in your body. Why? Cortisol induces insulin resistance…and it peaks around 7:00 am. What else happens around 7:00 am? Breakfast.

What do many people eat for breakfast? High-glycemic carbs like cereal. So, if the time of day where you’re most insulin resistant coincides with the time of day where you may be eating the most carbs,  that might explain why your blood sugars spike so much.

What is one thing that you can do to reduce the frequency of that? It’s simple. Consider a lower-carb breakfast option. Now, I’m not saying you have to get rid of all of your carbs at breakfast–I’m just advocating to consider decreasing the amount of carbs you eat at breakfast if you notice you are perpetually having high blood sugars afterwards.

2. Caffeine

What is one of the staples in most people’s early morning meal? Coffee.

Why is that significant to you and your blood sugar? Caffeine can cause the liver to release glycogen, aka stored glucose, into the bloodstream. When that happens, your blood sugar starts to go up, despite coffee not having any carbs on its own (unless you add things to it).

If you’ve been drinking coffee for a while without taking any sort of consideration as to your blood sugars, and suddenly you’re noticing it’s trending up slowly but surely every single time you have it, the coffee could be the culprit and may need to be considered when calculating your breakfast insulin dose.

3. Protein

As a dietitian, I am supposed to tell you to always have a “balanced meal.” You know what that means (*yawn*). Have your carb source, your veggie or fruit, and your protein!

At the end of the day, it’s up to you what you choose to eat. We’ve already covered the carb sources in part #1.

One of the other major components we haven’t talked about yet? Protein, which can actually raise your blood sugar, especially depending on the type of protein that is consumed. Different proteins may affect your blood sugar in different ways.

And if you’re someone who decides to go lower-carb at breakfast because of reason number one, don’t forget this: protein can impact your blood sugar by causing glucose release from the liver.

Think of it like in The Hunger Games, when the Katnis says, “I offer myself as tribute.”

That is what carbs are doing when protein is consumed with it. Carbs protect protein, but especially without the carbs, protein is more likely to trigger higher blood glucose levels. Just another consideration for you to make sure you are having awesome blood sugars early in the day. Isn’t diabetes and metabolism fun?

Read more about how to account for protein in your diet here: How to Calculate Bolus Insulin Dosing for Protein.

With all this information you’re probably thinking, “Well, why even bother eating breakfast at all?” And that’s the greatest thing: you have the choice. You don’t have to eat breakfast if you don’t want to. But, many people do, since it gives them a good boost to start off their day.

So, with these three handy tips, you can hopefully dial in on your blood sugars a little bit more, which will then allow you to be able to have an easier rest of your day. Because remember: the beginning of the day is going to have a major impact over how the rest is going to go.