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5 Surprising Foods That Can Spike Your Blood Sugar

It’s not just cookies, sodas and other sweet treats in the dessert aisle

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Sugar is sneaky. Just when you think you’ve got its whereabouts figured out, you begin taking a closer look at nutrition labels, only to discover the sweet stuff is hiding out in any number of foods and beverages not on the cookie, candy and soda aisles.

The unsavory truth: Sugar is used by all kinds of food manufacturers to enhance flavor and texture.

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In a study published in The Lancet Diabetes & Endocrinology, researchers conducted a survey of 1.2 million packaged foods and drinks purchased in the U.S. between 2000 and 2013 and found that a whopping 68 percent of them included added sweeteners. Some of them were the obvious culprits — soda, for instance — but many were not.

That, of course, makes it tricky for anyone watching their sugar consumption, in particular the 37 million people (1 in 10) in the U.S. with diabetes and the 96 million more with prediabetes who need to keep an eye on all carbohydrate consumption. . 

5 Unsuspecting Things That Spike Blood Sugar

According to the CDC, these 5 things can also boost your blood sugar:

  1. Sunburn: Blame the pain and stress, which increases blood sugar.
  2. Dehydration: Your blood sugar is more concentrated when there’s less water in the body.
  3. Losing sleep: Even just one bad night can affect how well your body uses insulin.
  4. Coffee: Yes, even without sweetener. “Some people’s blood sugar is extra-sensitive to caffeine,” the CDC says.
  5. Time of day: The later it gets, the harder it is to control blood sugar.

“High blood sugar levels in the diabetes and prediabetes ranges can cause serious damage throughout the body,” says Jill Weisenberger, a registered dietitian nutritionist in Virginia and author of Prediabetes: A Complete Guide. “We once thought that only people who had diabetes for some length of time had these problems. Now we have data that even people with prediabetes have a number of problems due to high blood sugar.”

Pointing to the research, Weisenberger says about 14 percent of people with prediabetes have eye disease from high blood sugar; nearly 18 percent have chronic kidney disease; and 11 to 25 percent of people with prediabetes have nerve damage.

Complicating matters: More than 80 percent of people with prediabetes don’t realize they have it, according to the Centers for Disease Control and Prevention (CDC).

Regardless of whether you have prediabetes, diabetes or none of the above, you should aim to limit big spikes in your blood sugar, says Vandana Sheth, a registered dietitian nutritionist and spokesperson for the Association of Diabetes Care & Education Specialists: “Big fluctuations in blood sugar, specifically spikes, can cause damage to the blood vessels, increasing the risk of stroke and heart disease.”

Keep reading to learn more about the surprising foods that can spike your blood sugar.

1. Refined grains

White bread and bagels, white rice, regular pasta and other foods that have been made with white flour have been stripped of the fiber and other key nutrients found in their whole-grain counterparts. Sure, some have been “enriched,” which means essential vitamins and minerals have been added back in during processing, but they still have what’s known as a high glycemic index (GI). High-GI foods are digested quickly and, as a result, they’re more likely to spike blood sugar.


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Instead: The American Diabetes Association recommends subbing with whole grains. Not only do foods like brown rice, barley, bulgur, quinoa and farro (all good substitutes for white rice), whole-grain bread and whole-wheat pasta provide fiber and essential minerals and vitamins like B and E, they’re low-GI foods. Foods that rank low on the glycemic index are digested more slowly and are less likely to cause rapid spikes in blood sugar. Not sure if that loaf of bread or package of pasta is a good choice? Look for “whole grain” or “whole wheat” at the top of the list of ingredients.

2. Plant-based milks

If you’ve adopted at least some part of a plant-based diet in the name of better health for both you and the planet, you’re not alone. A report from the International Food Information Council found that more than 40 percent of consumers assume a product described as “plant-based” is healthier than one that isn’t; 24 percent are consuming more plant-based dairy.

But here’s the rub: Some plant-based milks — meaning oat milk, almond milk, soy milk, rice milk, the list goes on — can have a lot of added sugar. In a study of 17 milk substitutes, published in Plant Foods for Human Nutritionresearchers found that plant-based milks can vary substantially in terms of nutrition. Some were very low in protein and had a high GI. The researchers’ conclusion? Some plant-based milk substitutes shouldn’t be perceived as healthy; they should be considered a treat.

Instead: If you prefer plant-based over cow’s milk (or have an allergy or intolerance), be sure to check the nutrition label first. Whatever your milk of choice, “consider drinking with a meal or a snack that provides more protein and some fat to decrease the spike in blood sugar,” Sheth advises.

3. Sugar-free snacks

As counterintuitive as it may seem, recent research suggests anything containing a sugar substitute — whether it’s “zero-sugar” chocolate, sugar-free protein bars, cookies or candy — may up your risk of developing insulin resistance, a precursor to diabetes.

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Instead: The ADA gives a partial green light to using artificial sweeteners in place of sugar as a way to combat obesity, metabolic syndrome and diabetes, with this word of caution: Claims like “sugar-free,” “reduced sugar” or “no sugar added” do not necessarily mean carbohydrate-free or lower in carbs than the original version of the food. Not sure? “It’s a good idea to meet with a registered dietitian at least once to get a good understanding of these foods,” says Revital Gorodeski Baskin, M.D., an endocrinologist and obesity program director at the Diabetes and Obesity Center at University Hospitals in Beachwood, Ohio.

4. Dried fruit

Dried fruit can be a healthy and convenient snack choice, but beware: Some food makers add sugar in the drying process. It’s also easy to eat a lot in one sitting, so the calories will add up.

Instead: While fresh fruit is the preferred choice, some are better than others. “Fruit such as watermelon, grapes and bananas contain very high quantities of simple sugar,” Baskin says. “Focus more on the berries family — strawberries, raspberries, blueberries, blackberries. They tend to have lower sugar levels.” Indeed, the American Diabetes Association (ADA) includes berries on its list of “superstar foods.”  

5. Diet soda

Although diet soda is obviously free of sugar, new research suggests it may still play a role in altering blood sugar levels. In a study published in 2022 in the journal Cell, researchers looked at four sugar substitutes and found that they don’t travel through the body without consequence.

Two of the artificial sweeteners — saccharin and sucralose — altered gut bacteria in a way that, at times, may change blood sugar levels. The researchers noted that it’s too soon to recommend permanently canning that can of diet soda.

“We know for certain that too much added sugar spikes blood sugar and can lead to other health problems,” Weisenberger says. “If the choice is regular or diet soda, I recommend diet soda. A diet soda every now and then — I drink one or so a month — is unlikely to hurt you.”

Instead: Substitute diet soda with seltzer or sparkling water flavored with a squeeze of lemon, lime or orange juice. “They are the best choices,” Weisenberger says.

Video: Control Your Blood Sugar with Weights and Walking

Editor’s note: This story, first published March 9, 2023, has been updated to include new information.

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