If you start your day with a steaming hot cup of coffee, you’re not alone. I’m right there with you, as are the other 7 out of 10 Americans who drink the bean juice daily. While coffee can increase alertness, focus, and just make it easier to get out of bed in the morning, it could be wreaking havoc on your blood sugar.
Black coffee has many health benefits thanks to its high antioxidant content, and it has even been found to reduce the risk of type 2 diabetes. But, the caffeine found in coffee can have a significant effect on your blood sugar, especially if you already have diabetes or prediabetes. One 12-ounce cup of coffee (about the size of a standard coffee mug) has around 140 milligrams of caffeine.
So if you’re watching your blood sugar levels, the worst coffee habit you can have is drinking it before you eat breakfast. In a 2020 study, British researchers found that drinking two cups of coffee before eating breakfast increased blood sugar levels by up to 50%.
Read on to learn more, and for more healthy coffee tips check out What Coffee Does to Your Blood Pressure.
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There are two main ways drinking caffeinated coffee before eating your morning meal can cause higher blood sugar.
First, a protein called adenosine is blocked by caffeine. Adenosine helps to tell your body how much insulin to make and helps your cells effectively respond to insulin. Drinking coffee before you eat can cause less insulin to be released and make your cells less receptive to it, leading to higher blood sugars.
The second way the caffeine in coffee can lead to higher blood sugar is from its ability to increase stress hormones, like cortisol and epinephrine, in the body. These hormones increase blood sugar as a way to have energy readily available to help combat whatever stress you’re facing. Insulin production goes down and your blood sugar rises.
So, while drinking coffee before eating is one of the worst things you can do for your blood sugar, you don’t have to give it up completely.
Waiting to have your coffee until after you eat a balanced breakfast can help lower the effect it has on your blood sugar. If you need something to get you started in the morning, try drinking a cup of tea, half-caf coffee, or just limit the portion of your coffee to 6 ounces. The less of it you drink before your morning meal, the less impact it will have on your blood sugar.
Kelsey Lorencz, RDN
Kelsey Lorencz is a registered dietitian, freelance writer, nutrition consultant, and sustainable food blogger. Read more