If you have diabetes, the foods that cause the most trouble are those that send your blood sugar surging quickly or make your body less responsive to insulin over time. That means some of the biggest offenders aren’t just sweets. White bread, sugary drinks, and even certain “healthy” choices like flavored yogurt or dried fruit can spike your glucose in ways you might not expect. Here’s a practical breakdown of what to limit or avoid, and why each category matters for blood sugar control.
Sugary Drinks Are the Single Worst Offender
Soda, sweet tea, lemonade, fruit punch, and energy drinks deliver a concentrated hit of sugar with zero fiber or protein to slow absorption. Your blood sugar rises fast, and for people with diabetes, it stays elevated longer than it should. A single 20-ounce bottle of soda can contain 65 grams of sugar, which is more than most people should consume in an entire day.
The fructose in these drinks is especially problematic. Unlike other sugars, fructose gets processed primarily by the liver, where it gets converted into fat. Research published in Circulation found that after just 10 weeks, people drinking fructose-sweetened beverages showed increased belly fat stored around their organs, higher fasting blood sugar, higher fasting insulin, and decreased insulin sensitivity, even compared to people who gained the same amount of weight from glucose-sweetened drinks. In other words, the type of sugar in most sodas and juice drinks does damage beyond the calories alone.
Fruit juice, even 100% juice with no added sugar, acts similarly in your body. Without the fiber of whole fruit, the sugar absorbs almost instantly. Stick with water, unsweetened tea, or sparkling water with a squeeze of citrus.
White Bread, White Rice, and Refined Grains
Refined grains have had their fiber-rich outer layers stripped away during processing. What’s left is mostly starch, which your body converts to glucose rapidly. White bread, white rice, bagels, most crackers, and packaged breakfast cereals all score 70 or higher on the glycemic index, meaning they raise blood sugar nearly as fast as pure glucose.
Fiber is the key difference. It slows digestion and creates a more gradual rise in blood sugar. Whole oats, for example, are digested slowly and produce a much gentler glucose curve. Even how finely a grain is ground matters: finely milled flour breaks down faster than coarsely ground grain, so even “whole wheat” bread made from very fine flour can spike blood sugar more than you’d expect. Look for breads where you can see visible grain pieces, or switch to intact grains like steel-cut oats, quinoa, barley, or bulgur.
Packaged Snacks, Pastries, and Breakfast Cereals
Doughnuts, croissants, cakes, rice cakes, and most packaged breakfast cereals combine refined flour with added sugar, creating a double hit. These foods land in the high glycemic index category and often contain very little protein or fiber to buffer the glucose response. A bowl of sweetened cereal with skim milk can raise your blood sugar as sharply as a candy bar.
Granola bars and flavored oatmeal packets are common traps. They’re marketed as healthy but frequently contain 12 to 20 grams of added sugar per serving. If a packaged snack lists sugar, corn syrup, or any syrup in the first few ingredients, treat it the same way you’d treat a dessert.
Hidden Sugars in Savory Foods
Some of the most deceptive blood sugar spikes come from foods that don’t even taste sweet. The CDC specifically flags ketchup, jarred pasta sauce, barbecue sauce, and salad dressings as common sources of hidden added sugars. A half-cup serving of jarred marinara can contain 6 to 12 grams of added sugar. Barbecue sauce often packs 8 or more grams per two-tablespoon serving.
Flavored yogurt is another one. A single container of fruit-on-the-bottom yogurt can contain 20 to 30 grams of sugar. Plain yogurt with fresh berries gives you the same experience with a fraction of the glucose impact. When shopping, check the “added sugars” line on the nutrition label rather than total sugars, since that separates the naturally occurring sugars from what manufacturers put in.
Dried Fruit and Fruit in Syrup
Fresh fruit is generally fine for people with diabetes because the fiber slows sugar absorption. Dried fruit is a different story. Removing the water concentrates the sugar dramatically. A 100-gram serving of raisins contains 79 grams of carbohydrates with a glycemic load of 52, which is extremely high. Dates contain 75 grams of carbohydrates per 100 grams. For context, 100 grams of raisins is a small handful, and most people eat more than that in a sitting.
Canned fruit packed in syrup adds even more sugar on top of what the fruit naturally contains. If you buy canned fruit, choose varieties packed in water or their own juice. For dried fruit, a tablespoon of raisins on a salad is very different from snacking on a full bag. Portion size is everything here.
Fried Foods and Trans Fats
Deep-fried foods like french fries, fried chicken, and doughnuts create problems on multiple fronts. They’re typically coated in refined flour, adding fast-absorbing carbohydrates. They’re also high in fats that can worsen insulin resistance over time. Trans fats, which are still found in some fried and commercially baked goods, are particularly harmful. They alter your muscles’ ability to burn energy efficiently, which in turn promotes insulin resistance.
Even without trans fats, fried foods tend to be calorie-dense and easy to overeat. Baking, grilling, or air-frying gives you similar textures with far less metabolic fallout.
Alcohol Requires Caution, Not Necessarily Avoidance
Alcohol has a complicated relationship with blood sugar. Moderate drinking (one drink a day for women, up to two for men) may actually improve insulin sensitivity slightly. But more than three drinks daily leads to higher blood glucose and higher A1C levels over time.
The more immediate danger is hypoglycemia. If you take insulin or certain oral diabetes medications, alcohol can cause your blood sugar to drop dangerously low, sometimes hours after your last drink. Cocktails and mixed drinks add another layer of risk because they’re often loaded with sugary mixers. Beer and sweet wines carry significant carbohydrates as well. If you do drink, eat food alongside it, monitor your blood sugar before bed, and be aware that a low can hit well into the next morning. The sugar in the drink itself absorbs too quickly to protect you from a delayed drop later.
Diet Drinks and Artificial Sweeteners
Swapping regular soda for diet soda seems like an obvious win, but the picture is more nuanced than it appears. A 2022 randomized controlled trial published in Cell found that two common artificial sweeteners, saccharin and sucralose, altered gut bacteria in ways that impaired the body’s ability to handle glucose. Researchers confirmed the connection was causal by transplanting stool samples from affected participants into mice, which then developed the same glucose tolerance problems.
Not everyone was affected equally. Individual differences in gut bacteria at the start of the study predicted who would develop impaired glucose responses, meaning some people tolerate artificial sweeteners fine while others don’t. If you rely heavily on diet drinks and notice your blood sugar is harder to manage than expected, this could be a factor worth discussing with your care team. Water, unsweetened tea, and black coffee remain the safest zero-calorie options.
What Matters Most: The Overall Pattern
No single food will ruin your blood sugar management, and no single food will fix it. What matters is the pattern. A diet built around refined carbohydrates, sugary drinks, and processed snacks keeps your blood sugar on a roller coaster. A diet built around vegetables, whole intact grains, lean proteins, nuts, and moderate portions of fresh fruit keeps it steadier.
When reading labels, focus on three things: added sugars, total carbohydrates per serving, and fiber. Foods with higher fiber relative to total carbs will produce a slower, lower blood sugar response. And pay attention to portion sizes on the label, since manufacturers sometimes list unrealistically small servings to make the numbers look better. A bag of chips labeled “about 3 servings” is almost always eaten as one.