9 Surprising Foods That Can Raise Your Blood Sugar Levels

If you’re concerned about managing your blood sugar levels, you know it can take a lot of research to make sure you’re eating foods that are low in added sugars and refined carbohydrates. Even seemingly “healthy” and wholesome foods can cause your blood sugar levels to rise.

We spoke with Sarah Varghese, MD, to clue you in on common foods that may be secretly spiking your blood sugar. Dr. Varghese is an endocrinology, diabetes, and metabolism specialist at Our Lady of Lourdes Medical Center in Camden, New Jersey. 

Here are 9 everyone should know about, plus tips on how to detect surprising sources of sugar on your own.

The average, healthy adult should get less than 10 percent of their total calories from added sugars. Unlike natural sugars, such as those found in fruit and milk, added sugars are put into food during the cooking or manufacturing process.

Most people don’t need to limit natural sugar, but should stick to the recommended daily limit of added sugar. Exactly how that is depends on your diet’s total calories. If you eat 2500 calories per day, no more than 250 should be from added sugars and if you eat 2000, no more than 200 from added sugars. 

“The number one thing I tell people is to always to read nutrition labels for each and every product they purchase,” says Dr. Varghese. “Simply reading and being aware of the contents will make a difference in the amount of sugar you consume.”

Tracking your food and beverage intake can also help make you aware of just how much of the sweet stuff you're consuming. Jotting your daily consumption on a piece of paper works, but phone applications can be helpful, too. Apps, like Sharecare, available for iOS and Android make tracking easy. Just open the application and plug in the size and quality of your meal. 

A high sugar food might not cause a sharp blood sugar increase if it contains other nutrients like fiber, which slows the digestion of sugar. Often, the carbohydrate count can give you a better idea of how a food will actually impact your blood sugar, since it includes fiber, sugars and starches.  

The glycemic index (GI) can also help determine if you’re eating a secret sugar bomb. The GI tells you how quickly the carbs in a food will raise your blood sugar, compared to a reference food—usually a type of sugar called glucose or white table sugar itself (sucrose). It takes into account other nutrients like fat and fiber to help calculate how quickly your body will process the carbs.

Table sugar (sucrose) has a glycemic index between 65 and 68; glucose has a GI of 100. High glycemic foods, or ones that raise your blood sugar quickly, are assigned a number between 70 to 100. Foods that cause a gradual rise in blood sugar score lower. Low GI foods are ranked 55 or less.

Here are nine everyday foods that can send your blood sugar soaring.

Everyone should eat about one and half to two cups of fruit daily—even people with diabetes. But before you mindlessly munch on everything in the produce section, be aware that certain fruits are especially high in natural sugar and carbs. Keep track of fruit servings and, if you’re on a carb-restricted diet to control diabetes, count them towards your daily allowance.

“But I wouldn’t encourage all people with diabetes to eat high-sugar fruits like bananas,” says Dr. Varghese. If your blood sugar is poorly controlled, for example, consider low-sugar fruit options instead.

One large banana has a hefty 17 grams of natural sugar and 31 grams of carbohydrates. How will that impact your blood sugar?

• The average large banana has a glycemic index of 48. So it’ll raise your blood sugar in about half the time table sugar would.
• It has a glycemic load (GL) of 11. GL measures how much a food will raise your blood sugar (again, GI measures how fast). A GL under 10 is considered low; anything over 20 is high.

However, bananas do contain essential nutrients like potassium and vitamin C. Eat bananas alongside fiber-rich foods like oatmeal to help slow the digestion of their sugars, while still reaping their nutritional benefits. 

Plain rice cakes—the notorious diet food. You’ve probably force-fed yourself a few over the years when trying to slim down. And on paper, that makes sense: According to the nutrition facts label, rice cakes have little fat and calories, as well as almost no cholesterol or sugar.

But that’s not the whole story. They also lack protein and fiber, which help you feel full and keep your blood sugar steady. As a result, rice cakes have an incredibly high:

• Glycemic index at 82 (remember, table sugar is around 68 and glucose is 100)
• Glycemic load at 17 (2 teaspoons of table sugar is about 7)

That’s why you get so hungry after you eat them! They hike up your blood sugar, but when it drops, you wind up feeling famished and hypoglycemic. Your diet may then backfire if you reach for junk food to satisfy your cravings. (Try one of these simple and delicious anti-aging snacks instead.)

“Oatmeal in itself is a healthy, low-glycemic product,” says Dr. Varghese. “But the flavored oatmeals you get at the store have loads of added sugar to make them sell. My recommendation is to avoid pre-packaged and instant oatmeals and, if you’re making your own, don’t use sugar, honey or syrup.”

Instead, add flavor by sprinkling in:

• Cinnamon, nutmeg or chai spices
• Blueberries, which only contain about 7 grams of sugar per half-cup and are a brain-boosting food
• Heart-healthy walnuts
• Chia or flax seeds
• Vanilla or almond extract
• Low-fat milk

Using real oats doesn’t have to mean crazy cooking times. Buy the quick-cooking variety, make overnight oats or cook oats in a rice cooker/crockpot while doing other things. (1 cup of real oats has a medium GL and GI; less than 1 g sugar; 28 g carbs.)

“Ready-made pasta from the grocery store is often high in added sugars,” says Dr. Varghese. “And if you’re eating it alongside pasta, which in itself has a high glycemic index, it can end up spiking your blood sugar significantly.”

But you can make delicious pasta at home, she continues. Start with a simple garlic base, pour in a can of unsweetened tomatoes or tomato paste, and then add your favorite seasonings like basil or oregano. But be watchful about which products you’re using for your ingredients, as well as what you decide to pour your sauce over in the end, she cautions.

Check the nutrition facts labels on any canned or bottled ingredients to make sure they’re low in sugar and carbs. Opt for multigrain pasta instead of the traditional white kind for a lower glycemic index.

Brace yourself. One baked russet potato has a glycemic index of 111. That means if you poured glucose directly into your mouth, it would still take longer to raise your blood sugar. The potato would also spike your blood sugar more with its glycemic load of 33 (3.5 g sugar; 63 g carbs). Throw in salt and fat from butter or bacon bits and you’re taking “cheat day” to a whole new level.

If you absolutely need a potato fix, yams are a sugar-steady option with a GI of 54 and a GL of 20. (Just avoid “candied” yams, which may have added sugar, syrup and marshmallow toppings.) Grains like barley, quinoa and brown rice have even lower GIs and can make for filling, satisfying side dishes.

Okay, you could probably guess that coffee house specials of the Unicorn Frappuccino and mocha-schmoca variety pack some serious sucrose. No shocker there.

But you might not know exactly how much sugar comes in bottled coffee and tea beverages at the grocery store. If you’ve never flipped them over to check the nutrition facts, here’s how some popular products compare: 

• Starbucks Doubleshot Espresso: 17 g sugar, 18 g carbohydrates
• Snapple Peach Tea: 39 g sugar, 40 g carbohydrates
• Dunkin Donuts French Vanilla Iced Coffee: 45 g sugar, 47 g carbohydrates
• Illy Issimo Coffee, Mochaccino: 19 g sugar, 21 g carbohydrates

Check the nutrition label even if you think you’re buying a “plain” coffee or tea drink. The front label might not indicate the beverage is sweetened, but brands may still add sugar or flavor enhancers.

People eat yogurt and assume they’re being healthy because it’s marketed as a safe snack, even for people with diabetes, says Dr. Varghese. But that’s not always the case.

Again, always read the nutrition labels on products, including yogurts and other ‘healthy’ foods, she says. “Yogurt, specifically, already contains around 15 to 16 grams of natural sugar—if you choose plain Greek yogurt, it’s a bit lower at 6 to 9 grams. If you add honey, chocolate, fruit-on-the-bottom or any other toppings, you’re increasing the sugar content even more.”

“Some of the sweet, flavored yogurts may contain over 30 to 36 grams of carbohydrates,” Dr. Varghese cautions. “I recommend choosing a low-fat yogurt and topping it with fresh fruit or low-fat granola, instead.”

Fresh baked baguette with butter and jelly may be one of life’s great simple pleasures. But don’t indulge your Parisian side too often. Plain white baguette has a higher glycemic index than table sugar and comes alarmingly close to glucose at 95.

For a sugar-steady alternative at the sidewalk café, opt for smashed avocado or a poached egg on multigrain toast. A typical slice of cracked wheat bread has a medium glycemic index of 58, a GL of 12 and about 14 g carbs. The healthy fats in avocado or the protein from the egg will slow its digestion as well, keeping you full much longer than baguette.

Condiments like ketchup, barbeque sauce and others—everyday foods you may not consider sugary—can have surprisingly large amounts of added sugar, says Dr. Varghese.

“If you have diabetes, be aware of this and check the labels on condiment bottles. You can have ketchup and barbeque sauce, but enjoy them in moderation,” she recommends. “Know how much sugar is in your ketchup serving, how much is in your meal overall and portion your foods accordingly.” 

Read more from Dr. Varghese.