Sugar-Sweetened Drinks Are the Worst for Blood Sugar (Here's Why)

Q: What are the 5 worst foods for blood sugar?

Foods with lots of sugar and white flour like candy, soda, white bread, and sugary cereals cause blood sugar to spike quickly. Fried foods and processed snacks are also bad because they have added sugars and unhealthy fats that harm your blood sugar.

Q: What 7 fruits should diabetics avoid?

Fruits with the most sugar like dried raisins, dates, canned fruit in syrup, and fruit juice are hard on blood sugar. Tropical fruits like mangoes and pineapples also have lots of natural sugar that can raise blood sugar fast.

Q: What five foods lower your blood sugar?

Vegetables like broccoli and spinach, whole grains like brown rice, proteins like chicken and fish, and nuts help keep blood sugar steady. Beans and legumes are also great because they have fiber and protein that slow down sugar absorption.

Q: What should a diabetic never eat?

Diabetics should avoid sugary drinks, candy, white bread, and desserts because these cause dangerous blood sugar spikes. They should also limit fried foods, processed meats, and foods with added sugars since these make blood sugar control harder.

If you had to pick one worst food for blood sugar, sugar-sweetened drinks are probably it. Liquid sugar with no fiber hits your bloodstream instantly.

A 600ml bottle of soft drink delivers 60-70 grams of simple carbohydrate with zero protein, fat, or fiber to slow absorption. Your blood glucose spikes within 15-20 minutes.

But the real pattern is broader: refined carbohydrates eaten solo, in liquid form, or in huge portions spike you hardest. To flatten the curve, eat protein and vegetables before carbs, pick whole grains with at least 3-5 grams of fiber per serving, pair any refined carb with fat or protein, and keep portions to 30-45 grams of available carbs per meal.

Everyone’s glucose response is different though, so pay attention to your own patterns.

Why do sugar-sweetened drinks spike blood sugar so fast?

Liquid sugar skips most digestion. When you drink soft drink, juice, or sweetened coffee, the glucose and fructose move directly from your stomach into your small intestine. No chewing. No fiber matrix to slow absorption. No protein to trigger a gradual insulin response.

In my experience working with clients, a can of soft drink causes a sharper, faster spike than eating two slices of white bread. The bread at least requires some breakdown. The drink is absorbed immediately.

High-fructose corn syrup makes this worse. Fructose bypasses normal glucose metabolism and goes straight to your liver. When consumed in large amounts without fiber, it can contribute to insulin resistance over time.

This is why fruit juice causes problems even though whole fruit does not. The fiber in an orange slows everything down. The juice from three oranges delivers the sugar load instantly.

What are the 5 worst foods for blood sugar?

After sugar-sweetened drinks, these foods cause the biggest problems:

White bread and refined grains eaten alone. A bagel or two slices of white bread delivers 45-60 grams of rapidly digestible starch with minimal fiber. When you eat bread by itself, blood sugar rises fast. One of my clients used to eat toast for breakfast and crash by 10am every day. Adding eggs and avocado fixed it.
Breakfast cereals with added sugar. Most commercial cereals are processed grain with added sugar. Even the ones marketed as healthy often contain 10-15 grams of sugar per serving. The combination of refined grain and added sugar creates a double spike.
Pastries, cakes, and sweet baked goods. These combine white flour, sugar, and often unhealthy fats. A muffin from a cafe can contain 50-70 grams of carbohydrate with almost no fiber or protein.
White rice in large portions. Rice itself is not terrible, but a typical restaurant serving is 200-300 grams of cooked rice, delivering 60-90 grams of rapidly digestible carbohydrate. Eating vegetables and protein before the rice reduces the glucose spike significantly.
Potato products, especially fried or mashed. Hot chips, mashed potato, and instant potato flakes are all rapidly digestible starch. The processing breaks down the cellular structure, making the starch immediately available for absorption.

The glycemic index measures how fast a food raises blood glucose. High-glycemic foods produce significantly larger blood sugar spikes than low-glycemic alternatives.

But the glycemic index doesn’t tell the whole story. Portion size, what you eat the food with, and your individual metabolism all matter.

What 7 fruits should diabetics avoid?

This question assumes fruit is dangerous. It’s not. Whole fruit contains fiber, vitamins, and polyphenols that slow sugar absorption. In controlled studies, eating fruit does not worsen blood sugar control in people with diabetes.

The problem is fruit juice and dried fruit in large amounts. When you remove the fiber, you remove the protection:

Fruit juice. Apple juice, orange juice, and grape juice deliver 25-35 grams of sugar per cup with no fiber. This causes a rapid spike.
Dried fruit. Dates, raisins, and dried mango are concentrated sugar. Six dates contain 40 grams of carbohydrate. Eat them in small amounts with nuts or cheese.
Fruit smoothies with added sugar. A commercial smoothie often contains juice, frozen yogurt, and added sweeteners. You can easily consume 60-80 grams of carbohydrate in a single drink.

Fresh fruit like berries, apples, pears, and citrus are fine in normal portions. A medium apple contains about 25 grams of carbohydrate but also 4-5 grams of fiber. The fiber slows absorption.

When I work with clients, I tell them to eat the fruit, not drink it.

Tropical fruits like mango, pineapple, and watermelon have higher sugar content per serving, but they’re not forbidden. Just keep portions moderate and pair them with protein or fat. A slice of watermelon with cheese is completely fine.

What five foods lower your blood sugar?

No food directly lowers blood sugar like insulin does. But certain foods slow absorption, improve insulin sensitivity, or replace high-glycemic choices:

Lentils and legumes. Consuming about 110 grams of cooked lentils reduces postprandial blood glucose by 20% compared to starchy controls. Lentils contain protein, fiber, and slowly digestible starch. They also improve the glucose response to meals eaten later in the day.
Non-starchy vegetables. Leafy greens, broccoli, cauliflower, capsicum, and zucchini contain almost no available carbohydrate. They add volume and fiber to meals. Eating vegetables before carbohydrates significantly reduces glucose and insulin spikes.
Lean protein. Chicken, fish, eggs, and tofu don’t raise blood sugar. They slow gastric emptying, which delays carbohydrate absorption. Protein also stimulates insulin release in a controlled, sustained way.
Nuts and seeds. Almonds, walnuts, chia seeds, and flaxseeds provide fat, protein, and fiber. Adding 30 grams of almonds to a meal reduces the glucose spike from that meal. The fat slows digestion.
Whole grains with intact structure. Steel-cut oats, quinoa, barley, and brown rice contain more fiber than refined grains. Slowly digestible starches produce a slower, sustained glucose release compared to rapidly digestible carbohydrates.

The key is food sequencing. When you eat protein and vegetables before carbohydrates, your blood sugar rise is smaller and slower. This happens because protein and fiber delay gastric emptying. The carbohydrate enters your bloodstream gradually instead of all at once.

What should a diabetic never eat?

There are no absolutely forbidden foods, but some are hard to fit into a blood sugar management plan:

Sugar-sweetened beverages. Soft drink, energy drinks, sweetened iced tea, and fruit punch offer no nutritional value and cause immediate spikes.
Foods combining refined carbs and unhealthy fats. Donuts, pastries, fried dough, and commercially baked goods often contain trans fats or excessive saturated fat alongside refined flour and sugar. These worsen insulin resistance over time.
High-sodium processed foods. While not directly affecting blood sugar, processed meats, canned soups, and frozen meals high in sodium increase cardiovascular risk, which is already elevated in diabetes.
Alcohol in excess. Alcohol interferes with glucose metabolism and can cause delayed hypoglycemia, especially if you take insulin or certain medications.

I remember when one of my clients insisted she couldn’t give up her morning orange juice. She was drinking 500ml every day, which contained 50 grams of sugar. When she switched to eating an orange and drinking water, her morning blood sugar readings dropped from 9-10 mmol/L to 6-7 mmol/L within two weeks.

That single change made her feel less tired and more focused all morning.

Why does food processing matter more than the food itself?

The form of carbohydrate matters as much as the type. Whole oats and instant oats come from the same grain, but instant oats are pre-cooked and broken down. They cause a faster glucose spike because the starch is more accessible to digestive enzymes.

Food processing affects the glycemic response in several ways:

Particle size. Finely milled flour is digested faster than coarsely ground grain. This is why stone-ground bread causes a smaller spike than white bread.
Cooking method. Boiling pasta al dente (firm) produces a lower glycemic response than cooking it until soft. The starch structure stays more intact.
Industrial processing. Extrusion, puffing, and high-heat processing break down starch granules, making them rapidly digestible. Puffed rice cereal spikes blood sugar faster than cooked brown rice.
Added ingredients. Adding sugar, removing fiber, and stripping away protein all make foods digest faster.

This is why whole foods perform better than processed versions. An apple contains fiber that slows absorption. Apple juice doesn’t. A potato boiled with the skin has more fiber and a lower glycemic response than instant mashed potato flakes.

How does individual variation affect which foods spike your blood sugar?

In a study of 800 people consuming nearly 47,000 meals, researchers found high variability in blood glucose response to identical foods. One person might spike after eating a banana while another stays stable. This variability comes from differences in gut bacteria, body composition, physical activity, and metabolic health.

What I found working with clients is that individual testing reveals patterns. One client spiked hard after eating brown rice but handled sweet potato fine. Another could eat sourdough bread without issues but crashed after eating white bread. These differences are real and measurable.

If you want to know which foods spike your blood sugar, test systematically:

Eat the food in a controlled amount on an empty stomach.
Measure blood glucose before eating and at 30, 60, 90, and 120 minutes after.
Record the results and look for patterns.

Continuous glucose monitors make this easier. You can see in real time how different foods, meal timing, exercise, and stress affect your glucose levels. This data is more useful than generic advice.

What can you do right now to improve your blood sugar response?

Multiple strategies reduce postprandial glucose spikes. Use these together for the biggest effect:

Reduce total carbohydrate intake per meal. Aim for 30-45 grams of available carbs per meal. This usually means one serving of starch plus vegetables and protein.
Choose low-glycemic carbohydrates. Replace white rice, white bread, and instant oats with brown rice, whole grain bread, and steel-cut oats. Look for at least 3-5 grams of fiber per serving.
Eat protein and vegetables first. This delays gastric emptying and reduces the glucose spike from carbohydrates eaten afterward. It works every time.
Add fiber to meals. Aim for 25-35 grams of fiber per day. Fiber slows carbohydrate absorption and improves insulin sensitivity.
Pair carbs with fat or protein. Never eat a refined carbohydrate alone. Add cheese to crackers. Add almond butter to toast. Add avocado to rice.
Move after eating. A 10-15 minute walk after meals reduces postprandial glucose by activating muscle glucose uptake.

When replacing high-glycemic foods with lower-glycemic alternatives, you see results quickly. In one study, when 25 grams of carbohydrate from wheat, rice, or potato was replaced with lentils in muffins, chilies, and soups, glucose and insulin responses decreased significantly across all three food types. The effect was linked to higher protein and fiber content.

Frequently asked questions

Does eating sugar cause diabetes?

Eating sugar doesn’t directly cause type 2 diabetes, but consuming large amounts of added sugar contributes to weight gain, insulin resistance, and metabolic dysfunction over time. The mechanism is indirect.

Excess sugar intake leads to excess calorie intake, which leads to fat gain, particularly visceral fat around organs. Visceral fat releases inflammatory compounds that interfere with insulin signaling.

Can I eat fruit if I have diabetes?

Yes. Whole fruit contains fiber, vitamins, and antioxidants. In controlled trials, eating fruit does not worsen glycemic control in people with diabetes. Stick to fresh or frozen fruit, not juice or dried fruit. A typical serving is one medium piece of fruit or one cup of berries.

Is honey better than sugar for blood sugar?

No. Honey is about 80% sugar by weight. It raises blood glucose just like table sugar does. Honey contains trace amounts of antioxidants, but not enough to make a meaningful difference in blood sugar management. Treat honey the same way you treat sugar.

Do artificial sweeteners affect blood sugar?

Most artificial sweeteners don’t raise blood glucose directly because they’re not metabolized as carbohydrate. However, some research suggests they may affect gut bacteria and insulin sensitivity over time. The evidence is mixed.

If you use artificial sweeteners, monitor your response. Some people find they increase cravings for sweet foods.

Can I reverse high blood sugar with diet alone?

Many people with prediabetes or early type 2 diabetes can normalize blood sugar through diet and lifestyle changes. This requires sustained effort: reducing carbohydrate intake, losing 5-10% of body weight, increasing physical activity, and improving sleep.

If you’ve had diabetes for many years or have significant beta-cell dysfunction, you may need medication. Work with your doctor to monitor progress.

The bottom line

Sugar-sweetened drinks are the worst single food for blood sugar because they deliver liquid sugar with no fiber, protein, or fat to slow absorption. But focusing on one food misses the bigger pattern. Refined carbs eaten alone, in large portions, or in liquid form all spike blood glucose hard.

The solution is consistent: eat whole foods with fiber, pair carbs with protein and fat, control portions, and eat vegetables first. Test your own response to foods and adjust based on what you see.

Blood sugar management is individual, but the principles work for everyone.

About the author

Armstrong Lazenby

BSc (Human Nutrition) registered nutritionist. Bachelor of Science (Exercise Science major) Master of Sports Medicine.

Connect on LinkedIn →

Sugar-Sweetened Drinks Are the Worst for Blood Sugar (Here’s Why)