12 Foods You Probably Never Knew Were Bad For Blood Sugar

Maintaining healthy blood sugar levels is a challenge for many people, and knowing which foods affect it is crucial. According to the Centers for Disease Control (CDC), as of 2021, 37.3 million Americans have type 2 diabetes. As the Mayo Clinic notes, this condition arises when the body has problems using and regulating sugar, which leads to high blood sugar levels. The CDC also notes an additional 96 million American adults have prediabetes, and at least 8 out of 10 people with this condition don't even realize it.

But you don't need to be diabetic or prediabetic to feel the effects of a blood sugar spike. Healthline notes that short-term symptoms of high blood sugar — also called hyperglycemia — include fatigue, headaches, frequent urination, and blurred vision. Continued high blood sugar can lead to an increased risk of nerve damage, cardiovascular disease, organ damage, and kidney problems, per Better Health Channel.

Some foods and beverages are widely known to be bad for blood sugar levels, including candy and soda. Other foods, though, may be affecting your blood sugar without you even knowing; as WebMD notes, it's not just sugar that causes spikes. Here's a look at 12 foods you probably didn't know are bad for blood sugar and how you might counter the effects.

If you thought potatoes were popular, you should hear about rice. White rice is by far the most common variety since it's easier to transport, cooks faster, and has a longer shelf life (via Financial Review). However, this comes at a cost. Healthline notes that white rice is refined to remove the bran and germ. Among other things, this means your body digests it faster, which causes blood sugar rushes. A 2012 research review by the Harvard School of Public Health found regular consumption of white rice can increase the risk of developing type 2 diabetes. Harvard Medical School puts it more bluntly, saying that eating white rice "has almost the same effect as eating pure table sugar."

There are alternatives, though — and you don't even need to give up rice. Heathline adds that unrefined brown rice has a glycemic index of 50 compared to white rice's 89 on a scale of 100. This means brown rice digests slower, and it also has more fiber, niacin, magnesium, and other key nutrients. 

A 2018 study published by The Journal of Nutrition found another interesting alternative. As summarized by Science Daily, researchers at the University of Guelph discovered that by swapping half your rice portion for lentils, you can lower blood sugar levels by 20%. Not only that, but the results were similar regardless of the type of lentil.

It's easy to think of fruit juice as a healthy alternative to soda and energy drinks. After all, it has "fruit" right in the name. But research indicates these drinks aren't all they're cracked up to be — especially fruit juice cocktails. As Medical News Today notes, fruit punch and other beverages often contain very little real fruit juice and a huge dose of sugar, corn syrup, or other sweeteners. For example, Ocean Spray Original Cranberry Juice Cocktail is only 27% juice and contains 23 grams of added sugar per serving. A 2015 study in the British Medical Journal found fruit juice cocktails can cause the same blood sugar spikes and increased risk of type 2 diabetes as soda does.

Fortunately, it appears that 100% fruit juice is a better blood sugar alternative. A 2017 Journal of Nutritional Science review concluded that 100% fruit juice "does not have a significant effect on glycaemic (sic) control or measures of insulin resistance." Still, Diabetes Self-Management notes that 100% juices do have a lot of natural sugar and carbohydrates. They also note juice doesn't contain fiber like fresh fruit does and is much easier to overconsume. As such, they recommend watching your juice portions and drinking it as part of a meal — and opting for fresh fruit whenever possible.

Some types of oatmeal are considered fine for blood sugar, but instant oats are another story. As detailed by Diabetes Strong, instant oats (aka quick oats) have been processed more than steel-cut or rolled oats. While this allows them to cook faster and still maintain similar nutritional properties to rolled oats, it also increases their glycemic index (GI) since the oats are digested faster. A systematic review in the British Journal of Nutrition found that steel-cut and rolled oats have a GI of 53-55 while instant oats have a GI of 71-75. In turn, these oats showed a higher glycemic response — in other words, a blood sugar spike.

Further complicating things is that many instant oats also have added sugars and sweeteners. For example, according to Nutritionix, Quaker Instant Oatmeal Maple and Brown Sugar has 12 grams of sugar and 33 grams of carbohydrates.

Conversely, Quaker Oats Old Fashioned rolled oats have only 1 gram of sugar and 27 grams of carbs. They also have more fiber and protein, which help slow digestion. Sticking with the less-processed steel-cut oats or rolled oats will help regulate your blood sugar while providing additional health perks compared to highly refined instant oats or breakfast cereals (via Healthline).

For many years, artificial sweeteners were considered safe options for blood sugar levels and even a "free food" for diabetics, as detailed in this 2017 Healthline article. But more recent research indicates that, at least for certain sweeteners, things aren't as rosy as previously thought. In fact, multiple studies have indicated that certain sugar substitutes can actually increase blood sugar.

In a 2022 study published by Cell, researchers found that consuming saccharin and sucralose significantly spiked the blood sugar levels of participants. Two separate studies in Diabetes Care and the Journal of Family Medicine and Primary Care also found that sucralose can increase the body's glycemic and insulin responses — and could further increase insulin resistance in those who already have type-2 diabetes. Finally, NBC News notes a growing consensus that artificial sweeteners hurt the body's ability to process actual glucose, which elevates the risk of diabetes and cardiovascular diseases.

It's not all bitter, though. A 2020 study in the Avicenna Journal of Phytomedicine determined that stevia, another popular non-nutritive sweetener, had no significant effect on blood glucose and insulin levels. Still, the evidence is clear that people shouldn't treat artificial sweeteners as a "get out of jail free" card when it comes to blood sugar and their overall health.

Honey has long been considered a healthy alternative to white table sugar. And, as Medical News Today notes, it does contain many beneficial nutrients, such as amino acids, antioxidants, vitamins, and minerals. But in terms of blood sugar, the gap may not be so big. According to WebMD, honey has a glycemic index score of 58, which is only two points lower than white sugar, and 1 tablespoon of raw honey contains 17 grams of total sugar from glucose and fructose. Medical News Today observes that honey actually has more sugar by volume than white sugar.

Research varies somewhat on exactly how much honey affects blood glucose levels. A study in the Journal of Medicinal Food in 2004 found that, while honey initially raises blood sugar, levels return to normal sooner than they do with white sugar. However, in 2009, an eight-week clinical trial determined that adding honey to the diets of type 2 diabetics significantly increased overall blood sugar levels, though it did provide other benefits, such as healthier body weight and cholesterol levels (via International Journal of Food Science and Nutrition).

The obvious conclusion is that it's possible to consume too much honey or white sugar. If choosing honey, Medical News Today recommends dark and raw varieties since these are more nutrient-rich.

A bagel is seen by many as a healthier morning replacement for donuts, pastries, and other sugar-loaded bread products. But when it comes to blood sugar, perception and reality don't mix.

Although bagels and English muffins don't have much pure sugar, Medical News Today notes that they are made with a lot of processed sugar and flour, turning them into landmines of starchy carbs. As the Gaples Institute adds, those carbohydrates are ultimately converted into sugar anyway during digestion. As a result, the average bagel has a glycemic load (GL) of 33, which is nearly double the average glazed donut.

Not sure what that means? Oregon State University explains that glycemic load is a variation of the glycemic index that adjusts for serving size. Any GL score of 20 or more is considered high, which makes that 33 even more mind-boggling.

If you're still craving a bagel, Livestrong suggests going with whole grain types that are balanced by fruits, protein, and other food groups. A bagel sandwich is a great example. They also recommend eating mini bagels instead of large ones and counting a bagel as multiple starchy food servings in your diet plan. Even something as simple as adding cream cheese to your bagel can reduce glucose swings (via Insider).