By Franziska Spritzler, RD, CDE
Diabetes is a chronic disease that has reached epidemic proportions among adults and children worldwide.
Uncontrolled diabetes has many serious consequences, including heart disease, kidney disease, blindness and other complications.
Prediabetes has also been linked to these conditions.
Importantly, eating the wrong foods can raise your blood sugar and insulin levels and promote inflammation, which may increase your risk of disease.
This article lists 11 foods that people with diabetes or prediabetes should avoid.
Why Does Carb Intake Matter for People With Diabetes?
Carbs, protein and fat are the macronutrients that provide your body with energy.
Of these three, carbs have the greatest effect on your blood sugar by far. This is because they are broken down into sugar, or glucose, and absorbed into your bloodstream.
Carbs include starches, sugar and fiber. However, fiber isn’t digested and absorbed by your body in the same way other carbs are, so it doesn’t raise your blood sugar.
Subtracting fiber from the total carbs in a food will give you its digestible or “net” carb content. For instance, if a cup of mixed vegetables contains 10 grams of carbs and 4 grams of fiber, its net carb count is 6 grams.
When people with diabetes consume too many carbs at a time, their blood sugar levels can rise to dangerously high levels.
Over time, high levels can damage your body’s nerves and blood vessels, which may set the stage for heart disease, kidney disease and other serious health conditions.
Maintaining a low carb intake can help prevent blood sugar spikes and greatly reduce the risk of diabetes complications.
Therefore, it’s important to avoid the foods listed below.
1. Sugar-Sweetened Beverages
Sugary beverages are the worst drink choice for someone with diabetes.
To begin with, they are very high in carbs, with a 12-ounce (354-ml) can of soda providing 38 grams.
The same amount of sweetened iced tea and lemonade each contain 36 grams of carbs, exclusively from sugar .
In addition, they’re loaded with fructose, which is strongly linked to insulin resistance and diabetes. Indeed, studies suggest that consuming sugar-sweetened beverages may increase the risk of diabetes-related conditions like fatty liver .
What’s more, the high fructose levels in sugary drinks may lead to metabolic changes that promote belly fat and potentially harmful cholesterol and triglyceride levels.
In one study of overweight and obese adults, consuming 25% of calories from high-fructose beverages on a weight-maintaining diet led to increased insulin resistance and belly fat, lower metabolic rate and worse heart health markers.
To help control blood sugar levels and prevent disease risk, consume water, club soda or unsweetened iced tea instead of sugary beverages.
Summary: Sodas and sweet drinks are high in carbs, which increase blood sugar. Also, their high fructose content has been linked to insulin resistance and an increased risk of obesity, fatty liver and other diseases.
2. Trans Fats
Industrial trans fats are extremely unhealthy.
They are created by adding hydrogen to unsaturated fatty acids in order to make them more stable.
Trans fats are found in margarines, peanut butter, spreads, creamers and frozen dinners. In addition, food manufacturers often add them to crackers, muffins and other baked goods to help extend shelf life.
Although trans fats don’t directly raise blood sugar levels, they’ve been linked to increased inflammation, insulin resistance and belly fat, as well as lower “good” HDL cholesterol levels and impaired arterial function.
These effects are especially concerning for people with diabetes, as they are at an increased risk of heart disease.
Fortunately, trans fats have been outlawed in most countries, and in 2015 the FDA called for their removal from products in the US market to be completed within three years.
Until trans fats are no longer in the food supply, avoid any product that contains the words “partially hydrogenated” in its ingredient list.
Summary: Trans fats are unsaturated fats that have been chemically altered to increase their stability. They have been linked to inflammation, insulin resistance, increased belly fat and heart disease.
3. White Bread, Pasta, and Rice
White bread, rice, and pasta are high-carb, processed foods.
Eating bread, bagels and other refined-flour foods has been shown to significantly increase blood sugar levels in people with type 1 and type 2 diabetes.
And this response isn’t exclusive to wheat products. In one study, gluten-free pastas were also shown to raise blood sugar, with rice-based types having the greatest effect.
Another study found that a meal containing a high-carb bagel not only raised blood sugar but also decreased brain function in people with type 2 diabetes and mental deficits.
These processed foods contain little fiber, which helps slow down the absorption of sugar into the bloodstream.
In another study, replacing white bread with high-fiber bread was shown to significantly reduce blood sugar levels in people with diabetes. In addition, they experienced reductions in cholesterol and blood pressure.
Summary: White bread, pasta and rice are high in carbs yet low in fiber. This combination can result in high blood sugar levels. Alternatively, choosing high-fiber, whole foods may help reduce blood sugar response.
4. Fruit-Flavored Yogurt
Plain yogurt can be a good option for people with diabetes. However, fruit-flavored varieties are a very different story.
Flavored yogurts are typically made from non-fat or low-fat milk and loaded with carbs and sugar.
In fact, a one-cup (245-gram) serving of fruit-flavored yogurt may contain 47 grams of sugar, meaning nearly 81% of its calories come from sugar.
Many people consider frozen yogurt to be a healthy alternative to ice cream. However, it can contain just as much or even more sugar than ice cream.
Rather than choosing high-sugar yogurts that can spike your blood sugar and insulin, opt for plain, whole-milk yogurt that contains no sugar and may be beneficial for your appetite, weight control and gut health.
Summary: Fruit-flavored yogurts are usually low in fat but high in sugar, which can lead to higher blood sugar and insulin levels. Plain, whole-milk yogurt is a better choice for diabetes control and overall health.
5. Sweetened Breakfast Cereals
Eating cereal is one of the worst ways to start your day if you have diabetes.
Despite the health claims on their boxes, most cereals are highly processed and contain far more carbs than many people realize.
In addition, they provide very little protein, a nutrient that can help you feel full and satisfied while keeping your blood sugar levels stable during the day.
Even “healthy” breakfast cereals aren’t good choices for those with diabetes.
For instance, just a half-cup serving (55 grams) of granola cereal contains 30 grams of digestible carbs, and Grape Nuts contain 41 grams. What’s more, each provides only 7 grams of protein per serving.
To keep blood sugar and hunger under control, skip the cereal and choose a protein-based low-carb breakfast instead.
Summary: Breakfast cereals are high in carbs but low in protein. A high-protein, low-carb breakfast is the best option for diabetes and appetite control.
6. Flavored Coffee Drinks
Coffee has been linked to several health benefits, including a reduced risk of diabetes.
However, flavored coffee drinks should be viewed as a liquid dessert, rather than a healthy beverage.
Studies have shown your brain doesn’t process liquid and solid foods similarly. When you drink calories, you don’t compensate by eating less later, potentially leading to weight gain.
Flavored coffee drinks are also loaded with carbs. Even “light” versions contain enough carbs to significantly raise your blood sugar levels.
For instance, a 16-ounce (454-ml) caramel frappuccino from Starbucks contains 67 grams of carbs, and the same size caramel light frappuccino contains 30 grams of carbs.
To keep your blood sugar under control and prevent weight gain, choose plain coffee or espresso with a tablespoon of heavy cream or half and half.
Summary: Flavored coffee drinks are very high in liquid carbs, which can raise blood sugar levels and fail to satisfy your hunger.
7. Honey, Agave Nectar, and Maple Syrup
People with diabetes often try to minimize their intake of white table sugar, as well as treats like candy, cookies and pie.
However, other forms of sugar can also cause blood sugar spikes. These include brown sugar and “natural” sugars like honey, agave nectar and maple syrup.
Although these sweeteners aren’t highly processed, they contain at least as many carbs as white sugar. In fact, most contain even more.
Below are the carb counts of a one-tablespoon serving of popular sweeteners:
- White sugar: 12.6 grams
- Agave nectar: 16 grams
- Honey: 17 grams
- Maple syrup: 13 grams
In one study, people with prediabetes experienced similar increases in blood sugar, insulin and inflammatory markers regardless of whether they consumed 1.7 ounces (50 grams) of white sugar or honey.
Your best strategy is to avoid all forms of sugar and use natural low-carb sweeteners instead.
Summary: Honey, agave nectar and maple syrup are not as processed as white table sugar, but they may have similar effects on blood sugar, insulin and inflammatory markers.
8. Dried Fruit
Fruit is a great source of several important vitamins and minerals, including vitamin C and potassium.
When fruit is dried, the process results in a loss of water that leads to even higher concentrations of these nutrients.
Unfortunately, its sugar content becomes more concentrated as well.
One cup of grapes contains 27 grams of carbs, including 1 gram of fiber. By contrast, one cup of raisins contains 115 grams of carbs, 5 of which come from fiber (43, 44).
Therefore, raisins contain more than three times as many carbs as grapes do. Other types of dried fruit are similarly higher in carbs when compared to fresh fruit.
If you have diabetes, you don’t have to give up fruit altogether. Sticking with low-sugar fruits like fresh berries or a small apple can provide health benefits while keeping your blood sugar in the target range.
Summary: Dried fruits become more concentrated in sugar and may contain more than three times as many carbs as fresh fruits do. Avoid dried fruit and choose fruits low in sugar for optimal blood sugar control.
9. Packaged Snack Foods
Pretzels, crackers and other packaged foods aren’t good snack choices.
They’re typically made with refined flour and provide few nutrients, although they have plenty of fast-digesting carbs that can rapidly raise blood sugar.
Here are the carb counts for a one-ounce (28-gram) serving of some popular snacks:
- Saltine crackers: 21 grams of carbs, including 1 gram of fiber
- Pretzels: 22 grams of carbs, including 1 gram of fiber
- Graham crackers: 21 grams of carbs, including 1 gram of fiber
In fact, some of these foods may contain even more carbs than stated on their nutrition label. One study found that snack foods provide 7.7% more carbs, on average, than the label states.
If you get hungry in between meals, it’s better to eat nuts or a few low-carb vegetables with an ounce of cheese.
Summary: Packaged snacks are typically highly processed foods made from refined flour that can quickly raise your blood sugar levels.
10. Fruit Juice
Although fruit juice is often considered a healthy beverage, its effects on blood sugar are actually similar to those of sodas and other sugary drinks.
This goes for unsweetened 100% fruit juice, as well as types that contain added sugar. In some cases, fruit juice is even higher in sugar and carbs than soda.
For example, 8 ounces (250 ml) of unsweetened apple juice and soda contain 24 grams of sugar each. An equivalent serving of grape juice provides 32 grams of sugar.
Like sugar-sweetened beverages, fruit juice is loaded with fructose, the type of sugar that drives insulin resistance, obesity and heart disease.
A much better alternative is to enjoy water with a wedge of lemon, which provides less than 1 gram of carbs and is virtually calorie-free.
Summary: Unsweetened fruit juice contains at least as much sugar as sodas do. Its high fructose content can worsen insulin resistance, promote weight gain and increase the risk of heart disease.
11. French Fries
French fries are a food to steer clear of, especially if you have diabetes.
Potatoes themselves are relatively high in carbs. One medium potato with the skin on contains 37 grams of carbs, 4 of which come from fiber.
However, once they’ve been peeled and fried in vegetable oil, potatoes may do more than spike your blood sugar.
Deep-frying foods has been shown to produce high amounts of toxic compounds like AGEs and aldehydes, which may promote inflammation and increase the risk of disease .
Indeed, several studies have linked frequently consuming french fries and other fried foods to heart disease and cancer.
If you don’t want to avoid potatoes altogether, eating a small amount of sweet potatoes is your best option.
Summary: In addition to being high in carbs that raise blood sugar levels, french fries are fried in unhealthy oils that may promote inflammation and increase the risk of heart disease and cancer.
The Bottom Line
Knowing which foods to avoid when you have diabetes can sometimes seem tough. However, following a few guidelines can make it easier.
Your main goals should include staying away from unhealthy fats, liquid sugars, processed grains and other foods that contain refined carbs.
Avoiding foods that increase your blood sugar levels and drive insulin resistance can help keep you healthy now and reduce your risk of future diabetes complications.
This article is reprinted with permission from Authority Nutrition.