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How Coffee Affects Blood Glucose Levels

Written by
Team Nutrisense
Reviewed by
Kara Collier
RDN, LDN, CNSC
a person holding a tray with a cup of coffee

If you're an avid coffee drinker, chances are you've thought about whether that morning cup has any effect on your blood glucose levels. If so, you're not alone. Some studies show that drinking coffee might cause some people to experience blood glucose spikes or crashes. Still, the effects of caffeine on your blood sugar are a little more complex than that.

If you want to understand what happens to your blood sugar when you drink coffee, it's crucial to know all of the factors that come into play when you’re drinking it. Even with all the information we’re about to give you, remember that everyone has different responses to different food and drink. To track how your body responds to coffee in real-time, consider getting yourself a continuous glucose monitor!

Coffee and Blood Glucose

a person making a cup of coffee

Coffee has been getting a lot of attention lately, especially for its possible ability to help with weight loss—although you may want to take that with a grain of salt. Research suggests that its polyphenols may have health benefits, including increasing insulin sensitivity, lowering blood pressure, and even reducing liver damage caused by chronic alcohol use.

Caffeine is a stimulant, so you may expect it to cause a larger glucose response, as it can stimulate our central nervous system and increase adrenaline in the bloodstream. This is partially correct—a recent review of clinical trials showed that although caffeine causes a temporary increase in glucose, due to a temporary reduction in insulin sensitivity for some. Still, some research also suggests that long-term consumption can improve glucose responses over time.

So, what can we take away from all of this? For starters, we know that everyone responds differently to caffeine, and the effects may be dose-dependent. For some people, coffee may lower blood glucose levels, but it may do just the opposite for others. 

Additionally, you may observe more benefits from drinking coffee long-term vs. acute increases in glucose. However, as with most things, its effects on blood glucose vary and are still being researched. It's essential to track, monitor, and remember that if it's negatively affecting your blood sugar levels or how you feel during the day, you should consider switching up your coffee intake.

Can Coffee Really Lower Your Blood Glucose Levels?

a cup of coffee, a smartphone and a note that says glucose heck

We've said this before, and we'll say it again—there's no one-size-fits-all when it comes to your health. With that in mind, remember that coffee can have different effects on different people. And for some, yes, it can lead to lower blood glucose levels.

Wondering why and how this might happen? Epidemiological research suggests the answer could lie not in the caffeine per se but the other components of the coffee bean. Certain bioactive compounds in coffee, particularly chlorogenic acids (CGA), are antioxidant-rich and have potent anti-inflammatory benefits that may improve glucose metabolism. Regular consumption of these powerful polyphenols may be the driving force behind the long-term glucose benefits observed in coffee drinkers. 

Not a coffee drinker? These powerful benefits don't just come from coffee! CGAs are also present in tea, berries, cocoa, and citrus fruits, to name a few.

Does the Amount of Caffeine Matter?

a person holding a huge cup of coffee

Don't start loading up on coffee to lower your blood glucose levels. Your response to caffeine will also depend on your baseline blood glucose level, how much caffeine you consume, genetics, and how your body handles caffeine. Most healthy people can safely consume up to 400 mg of caffeine per day without adverse side effects. 

One thing to consider is that your response may depend on more than just CGAs. Recent studies suggest the difference in your glucose response may stem from your genetic makeup, with specific genes linked to your rate of caffeine metabolism. For some, this could mean they metabolize coffee quicker, resulting in more dramatic glycemic responses from the same amount of caffeine.

Before you decide what a healthy level looks like for you, the best thing to do is to experiment and pay attention to your threshold to figure out how much caffeine is appropriate for your daily limit. Even if you're healthy, it's a good idea to consume caffeine in moderation and find what amount is right for you. Remember that, like everything else, caffeine has its side effects and risks. It can lead to headaches, restlessness, and anxiety. Certain types of coffee, like unfiltered coffee, can lead to an increase in cholesterol, and there may also be an increase in your risk of things like heartburn. And, of course, if you're loading up on the cream, milk, and sweetener, too, you may be putting yourself at risk of diabetes.

Common Types of Coffee and Your Blood Glucose

four cups of different coffee

There are many types of coffee, and so, caffeine content can vary. But let's start with a simple baseline. The average American will drink two cups of coffee per day, which is around 280 milligrams of caffeine in total. And the way your body responds can depend not just on the amount, but also on what type of coffee you're drinking. Here's a little more information about the different types and variations of America's favorite beverage.

Black Coffee

someone pouring black coffee in a cup

Whether you're making it by adding water to your espresso or using a drip coffeemaker, a cup of black coffee has around 80-100 milligrams of caffeine. While we've established it's also rich in antioxidants—the phytochemicals that promote health and fight free radicals in your body—too much caffeine can wreak havoc on sleep quality for some people and may work best in moderation. A cup or two a day may have cardiovascular benefits, including reducing risks associated with heart disease and Type 2 diabetes for some people.

Espresso

a cup of espresso

Small, strong shots of coffee that'll jolt you awake—who doesn't love an espresso? Espressos are made by grinding and roasting coffee beans, then passing a small amount of nearly boiling water through the ground coffee at high pressure. The result is a concentrated drink with a relatively strong taste and creamy texture.

When you drink it on its own, there are no significant amounts of naturally occurring sugars in a cup of espresso. Drinks with added sugars and flavors are more likely to produce bigger spikes in glucose and result in energy crashes or cravings throughout the day. A single serving of espresso contains about 60 milligrams of caffeine and may not produce much of an impact on glucose on its own. However, remember that caffeine can affect everyone differently, so higher doses may be essential to monitor. When we say a serving of espresso, we don't mean a cup full! Espresso servings are around 30 milliliters.

Espresso in Other Coffee

a person holding a cup of coffee

Espresso on its own is great, but it's often just one of the ingredients in other types of coffee. Everything from cappuccinos and lattes to Red-Eyes and Café Americano's include espresso shots, but because of the milk, cream and flavor additions, your body will likely respond to them differently.

Since espresso shots are a popular base for mixed coffee drinks, let's focus on those for a minute. With so many variables at play (genetics, duration of coffee consumption, and other additives, to name a few), it can be challenging to know how each type will impact your glucose. For example, a cappuccino is an espresso mixed into a cup of foamed milk, then topped with anything from cocoa powder and cinnamon to a range of other toppings.

A simple cappuccino made with plain milk and no added sugar provides around 160 milligrams of caffeine and 50-70 calories. It also has a lower glycemic index, around 35. Milk contains both protein and fat, which can slow digestion and allow for a more gradual glucose curve for most people. Any added sugars or flavorings could contribute to a larger glucose and insulin response.

Cold Brew

someone pouring Cold Brew in a glass

Technology has changed how we brew coffee, and you can now make more potent brews with fewer chemicals. If you're trying to watch your blood sugar but love coffee, try cold brewing it. Cold brewed coffee often has a fuller flavor and is less traditionally 'bitter' than regular brewed coffee, translating to it needing less sugar. This type of coffee may also be less acidic than regular hot coffee. For those with sensitive stomachs, this option may be easier to tolerate. As with all coffee drinks, the critical thing is to avoid high sugar flavoring, milk, and syrups to get an optimal response.

Decaffeinated Coffee

coffee beans

As we've touched on already, research suggests caffeine can improve glucose handling in the long run. Since decaf has around 2 milligrams of caffeine in a typical cup, the caffeine content may not impact blood glucose. Decaffeinated coffee still seems to have similar associations with a lower risk of developing some forms of glucose metabolism disorders as its caffeine-containing counterpart. It's likely because a cup of decaf also contains CGAs, and can provide similar benefits.

As you can see, it's not easy to give you a comprehensive list of how every single coffee type, flavor, and brew that exists will react to your system. When in doubt, the best way to find out is to learn how to monitor your glucose levels and track how your body responds to different types of coffee yourself.

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Engage with Your Blood Glucose Levels with Nutrisense

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