Whether it’s from coffee, tea, soda, or chocolate, most Americans get caffeine every day. For healthy people, it’s usually a harmless perk-me-up. But if you have type 2 diabetes, caffeine may make it harder to keep your blood sugar in check.
How Does Caffeine Affect Your Blood Sugar?
A growing body of research suggests people with type 2 diabetes react to caffeine differently. It can raise blood sugar and insulin levels for those with the disease.
One study looked at people with type 2 diabetes who took a 250-milligram caffeine pill at breakfast and another at lunchtime. That’s about the same amount as drinking two cups of coffee with each meal. The result: Their blood sugar was 8% higher than on days when they didn’t have caffeine. Their reading also jumped by more after each meal.
That’s because caffeine can affect how your body responds to insulin, the hormone that allows sugar to enter your cells and get changed into energy.
Caffeine may lower your insulin sensitivity. That means your cells don’t react to the hormone by as much as they once did. They don’t absorb as much sugar from your blood after you eat or drink. This causes your body to make more insulin, so you have higher levels after meals.
If you have type 2 diabetes, your body already doesn’t use insulin well. After meals, your blood sugar rises higher than normal. Caffeine may make it tougher to bring it down to a healthy point. This may lead to too-high blood sugar levels. Over time, this may raise your chance of diabetes complications, like nerve damage or heart disease.
Why Does Caffeine Have This Effect?
Scientists are still learning how caffeine affects your insulin and blood sugar levels. But they think it may work this way:
- Caffeine raises levels of certain stress hormones, like epinephrine (also called adrenaline). Epinephrine can prevent your cells from processing as much sugar. It may also keep your body from making as much insulin.
- It blocks a protein called adenosine. This molecule plays a big role in how much insulin your body makes. It also controls how your cells respond to it. Caffeine keeps adenosinewhich plays a big role in how much insulin your body makes.
- It takes a toll on your sleep. Too much caffeine can keep you awake. Lack of sleep may also lower your insulin sensitivity.
How Much Caffeine Is Too Much?
It only takes about 200 milligrams of caffeine to affect your blood sugar. That’s the amount in about one or two cups of brewed coffee or three or four cups of black tea.
You may be able to handle more or less caffeine. People can have different reactions to the drug. Your response depends on things like your age and weight.
How much caffeine you usually get may also play a role. People with diabetes who are regular coffee drinkers don’t have higher blood sugar levels than those who aren’t. Some experts think your body gets used to that amount of caffeineover time. But other research shows that caffeine could still cause a spike, even if you always start your day with a cup of joe.
To find out if caffeine raises your blood sugar, talk to your doctor or a dietitian. You might test your blood sugar throughout the morning after you have your usual cup of coffee or tea. Then you’ll test after you skip the drink for a few days. When you compare these results, you’ll know if caffeine has an impact.
What About the Caffeine in Coffee?
There’s another twist to the story. Studies show that coffee may lower your odds of getting type 2 diabetes in the first place. Experts think that’s because the drink is high in antioxidants. These compounds reduce inflammation in your system, which can raise your chance of having the disease.
If you already have type 2 diabetes, this may not hold true. The caffeine in a cup of java makes it tougher to control your blood sugar. If yours spikes after your morning cup, you may want to switch to decaf. Even though this drink has a tiny amount of caffeine, it doesn’t have the same effect on your blood sugar or insulin.
FAQs
How does coffee affect blood sugar? ›
Short-term studies showed that consumption of caffeinated coffee may increase the area under the curve for glucose response, while for long-term studies, caffeinated coffee may improve the glycaemic metabolism by reducing the glucose curve and increasing the insulin response.
Does coffee affect blood sugar diabetes? ›A growing body of research suggests people with type 2 diabetes react to caffeine differently. It can raise blood sugar and insulin levels for those with the disease.
Does black coffee effect blood sugar? ›Plain coffee does not seem to directly increase levels of blood sugar, or blood glucose. This is good news for people with diabetes who like black coffee. However, some research suggests that the caffeine in coffee could impair insulin sensitivity, which is not ideal for people with diabetes.
Will quitting coffee lower blood sugar? ›Our study suggests that one way to lower blood sugar is to simply quit drinking coffee, or any other caffeinated beverages. It may not be easy, but it doesn't cost a dime, and there are no side effects," Lane says. The study was funded by the National Institute of Diabetes, Digestive, and Kidney Disorders.
Should diabetics avoid coffee? ›In short, yes, it's safe to drink coffee if you have diabetes. Although the research on coffee's benefits is mixed, as long as you keep an eye on your blood sugar and stick to coffee with less sugar, drinking coffee shouldn't be dangerous. But make sure you limit your caffeine consumption to a reasonable amount.
Why does caffeine lower my blood sugar? ›Though it isn't often discussed, coffee, energy drinks, and other sources of caffeine can negatively impact our blood sugar levels by reducing insulin sensitivity.
What causes blood sugar to rise without eating? ›Physical or emotional stress triggers the release of hormones that can cause high blood sugar levels. Menstrual periods and menopause also cause changes in the hormones that affect blood sugar levels. Regular blood sugar testing can uncover patterns. This can help you and your health care team control your diabetes.
Does coffee affect a1c test? ›Can you drink coffee if you're fasting before a blood test? Even if you drink it black, coffee can interfere with blood test results. That's because it contains caffeine and soluble plant matter, which might skew your test results. Coffee is also a diuretic, which means that it will increase how much you pee.
Does caffeine spike blood sugar? ›Artificial sweeteners—more research is needed, but some studies show they can raise blood sugar. Coffee—even without sweetener. Some people's blood sugar is extra-sensitive to caffeine. Losing sleep—even just one night of too little sleep can make your body use insulin less well.
What drink lowers blood sugar? ›Drinking water regularly may rehydrate the blood, lower blood sugar levels, and reduce diabetes risk ( 20 , 21 ). Keep in mind that water and other zero-calorie drinks are best.
What should my blood sugar be when I wake up? ›
What should your blood sugar be when you wake up? Whenever possible, aim to keep your glucose levels in range between 70 and 130 mg/dL in the morning before you eat breakfast, and between 70 and 180 mg/dL at other times.
Which is better for diabetics tea or coffee? ›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.
Should diabetics eat after 7pm? ›If you have diabetes, late-night snacks aren't necessarily off-limits — but it's important to make healthy choices. Late-night snacks add extra calories, which can lead to weight gain.
How much can coffee raise your blood sugar? ›Each person's blood glucose levels were tested multiple times throughout the week, and it was found that those who drank caffeine had blood sugars around 8 percent higher than those who didn't take caffeine.
Does drinking water lower blood sugar? ›Drink plenty of water
Drinking plenty of water helps your kidneys flush out excess sugar. One study found that people who drink more water lower their risk for developing high blood sugar levels.
The dawn phenomenon
In the early hours of the morning, hormones, including cortisol and growth hormone, signal the liver to boost the production of glucose, which provides energy that helps you wake up. This triggers beta cells in the pancreas to release insulin in order to keep blood glucose levels in check.