Foods to avoid in prediabetes – Medical guide

When it comes to prediabetes, one of the most persistent myths is that simply cutting back on sugar is enough. The reality? Many supposedly “healthy” foods can spike your blood glucose just as much as candy bars. Understanding which foods to avoid with prediabetes requires looking beyond obvious sources of sugar to the hidden offenders that may be undermining your health daily.

Another common misconception: all whole foods are beneficial for prediabetics. Yet research reveals that certain fruits, whole grains, and even some vegetables can significantly impact blood sugar levels in those with insulin resistance. In fact, the glycemic impact of foods varies dramatically—a medium baked potato raises blood sugar more than a tablespoon of pure table sugar, despite being considered a “natural” food.

Perhaps most surprising is the belief that “low-fat” foods are ideal for metabolic health. Studies now show that many low-fat products replace fat with added sugars and refined carbohydrates—ingredients that can worsen insulin resistance and accelerate the transition from prediabetes to diabetes.

At IFitCenter, we’re examining the scientific evidence behind which foods truly deserve caution when managing prediabetes. This comprehensive guide cuts through marketing claims and outdated advice to provide you with clear, evidence-based recommendations on which foods might be silently sabotaging your blood sugar control.

The information in this article is provided for educational purposes only and is based on current scientific research related to prediabetes management. While we strive to present accurate and up-to-date information, this content should not be considered medical advice.
This information is designed to complement, not replace, the relationship between you and your healthcare professionals.

How Food Choices Impact Prediabetes Progression

Understanding which foods to avoid with prediabetes starts with recognizing how different foods affect your body’s glucose regulation system. When you consume any food containing carbohydrates, your body breaks these down into glucose, which enters your bloodstream. In response, your pancreas releases insulin—a hormone responsible for helping cells absorb this glucose from the blood.

For individuals with prediabetes, this glucose-insulin balance is already compromised. According to the American Diabetes Association Standards of Care, prediabetes represents a state of “reversible β-cell dysfunction,” unlike diabetes which indicates “established pancreatic failure.” This critical difference explains why dietary interventions can be particularly effective during the prediabetic stage.

“In my clinical experience, many patients don’t realize that prediabetes isn’t simply ‘less severe diabetes’ but rather a distinct metabolic state where pancreatic beta cells are struggling but not yet failing. This critical distinction explains why dietary intervention at the prediabetes stage is particularly effective—we’re supporting cellular function before permanent damage occurs, essentially giving overworked insulin-producing cells a chance to recover their normal function.”

Dr. Babak Jamalian, Family Physician.

Not All Foods Affect Blood Sugar Equally

One of the most important concepts for prediabetes diet foods to avoid is understanding that foods have dramatically different effects on blood sugar levels—even when they contain the same amount of carbohydrates. This difference is measured through what scientists call the glycemic index and glycemic load.

Consider this everyday example: a medium apple and a slice of white bread might contain roughly the same amount of carbohydrates (about 15 grams). However, the apple’s fiber slows down glucose absorption, resulting in a gradual rise in blood sugar. In contrast, the refined white bread quickly breaks down into glucose, causing a rapid spike in blood sugar levels—exactly what those with prediabetes should avoid.

With this understanding of how food choices directly impact prediabetes progression, let’s explore the specific food categories that research has identified as most problematic for blood sugar control.

To read more about prediabetes, I strongly recommend using the following links:

• What is Prediabetes?
• Signs and Symptoms of Prediabetes
• Difference Between Prediabetes and Diabetes
• The Connection Between Obesity and Prediabetes
• Can Prediabetes Be Reversed?
• How to Diagnosis Prediabetes?
• Prediabetes Reversal Through Weight Management
• Insulin Resistance and Diabetes

Foods with Added Sugars That Worsen Prediabetes

Added sugars represent one of the most significant categories of foods to avoid if you have prediabetes. According to research published in the American Diabetes Association Standards of Care, these sugars rapidly enter the bloodstream, triggering substantial insulin spikes that worsen insulin resistance. What makes added sugars particularly problematic is their prevalence—the average American consumes approximately 31 teaspoons daily, while normal blood sugar requires just one teaspoon in the entire bloodstream.

The “Metabolomics in Prediabetes and Diabetes” study published in Diabetes Care found that high sugar consumption elevates specific metabolites, particularly branched-chain amino acids, which are directly associated with a 35-36% higher diabetes risk. This biochemical connection explains why reducing added sugar intake is crucial for anyone with borderline diabetes.

Common Sources of Added Sugars to Eliminate

• Desserts and Pastries: A single slice of cake can contain up to 30g of added sugar, triggering prolonged blood glucose elevations.
• Candy and Chocolate: Even small portions cause dramatic blood sugar spikes due to their concentrated sugar content and lack of fiber or protein to slow absorption.
• Ice Cream and Frozen Treats: These combine sugar with fat, creating a particularly problematic combination for insulin resistance.
• Sweetened Yogurt: Many “healthy” yogurts contain more added sugar than a serving of ice cream.
• Breakfast Cereals: Even “whole grain” options often contain 12-15g of added sugar per serving.

Identifying Hidden Sugars on Food Labels

Manufacturers often disguise added sugars under different names to make products appear healthier than they are. When checking labels, look for these common sugar aliases:

Pay special attention to the “Total Sugars” and “Added Sugars” lines on nutrition facts panels. The American Heart Association recommends limiting added sugar to no more than 36g (9 teaspoons) daily for men and 25g (6 teaspoons) for women—but for those with prediabetes, even lower limits are beneficial.

Remember that ingredients are listed by weight, so when multiple sugar types appear on the label, the manufacturer may be using smaller amounts of several types to prevent sugar from appearing as the first ingredient—though collectively, they may still form the primary component.

Refined Carbohydrates to Avoid for Prediabetes Management

Refined carbohydrates rank among the most important foods to avoid when pre diabetic because they behave remarkably similarly to pure sugar in your body. When you consume refined carbs, digestive enzymes rapidly break them down into glucose molecules that enter your bloodstream almost as quickly as table sugar. According to research published in the American Diabetes Association Standards of Care, this rapid glucose absorption triggers substantial insulin release, which over time contributes to insulin resistance—the core issue in prediabetes.

The “Pre-Diabetes and What It Means” study found that regularly consuming high-glycemic carbohydrates increases diabetes risk by 4.3 times compared to those who limit these foods. This occurs because refined carbs lack the fiber, protein, and healthy fats that would normally slow digestion and provide a gradual release of glucose into the bloodstream.

Why These Foods Spike Blood Sugar Rapidly

Refined carbohydrates have had most of their natural fiber and nutrients removed during processing. Without fiber to slow digestion, these foods break down extremely quickly. As Dr. Berg explains, “A normal blood sugar is only a tiny bit—it’s like one teaspoon for all of your blood,” yet refined carbs can rapidly introduce much larger amounts of glucose into circulation, overwhelming your body’s glucose management system.

High-Glycemic Refined Carbs Pre-Diabetics Should Avoid

According to the metabolomics research published in Diabetes Care, high-glycemic foods consistently create metabolic profiles associated with increased diabetes risk. For context, pure glucose has a glycemic index of 100, while foods below 55 are considered low-glycemic alternatives that are generally better choices for people with prediabetes.

Better Alternatives to Consider

When avoiding these foods that worsen prediabetes, consider lower glycemic alternatives like:

• 100% whole grain breads (GI: 69)
• Brown rice or wild rice (GI: 50-55)
• Legume-based pasta or whole grain pasta (GI: 40-50)
• Steel-cut oats (GI: 55)
• Whole food snacks like nuts instead of crackers

The Diabetes Prevention Program research found that replacing refined carbohydrates with lower glycemic alternatives contributed significantly to the impressive 58% reduction in diabetes progression. Making these substitutions helps regulate blood glucose levels and reduces the strain on your insulin-producing cells.

Sugar-Sweetened Beverages That Increase Diabetes Risk

When identifying foods to avoid with prediabetes, sugar-sweetened beverages deserve special attention due to their particularly harmful effects on blood glucose. Unlike solid foods containing sugar, liquid calories bypass many of your body’s satiety mechanisms and deliver a concentrated dose of sugar directly to your bloodstream. Research from the Pre-Diabetes Epidemiological Evidence study shows that regular consumption of sugar-sweetened beverages is associated with a 26% increased risk of developing type 2 diabetes—making them among the most dangerous foods to avoid if you have prediabetes.

What makes these beverages especially problematic is their lack of fiber or protein that would normally slow sugar absorption. As Dr. Berg explains, “A normal blood sugar is only one teaspoon for all of your blood,” yet a single 12-ounce soda can contain up to 10 teaspoons of sugar—potentially overwhelming your insulin response and accelerating insulin resistance.

Beverages Prediabetics Should Eliminate

The metabolomics research published in Diabetes Care found that regular consumption of sugar-sweetened beverages leads to metabolic profiles associated increased diabetes risk. This is because liquid sugars are absorbed more rapidly than solid forms, creating dramatic blood glucose spikes that strain insulin-producing cells.

Hidden Sugars in “Healthy” Beverages

Many beverages marketed as “healthy” contain surprising amounts of sugar that can worsen prediabetes. Smoothies, vitamin waters, and “natural” fruit drinks often contain as much or more sugar than sodas. According to the ADA Standards of Care, beverages labeled “no added sugar” may still contain high levels of natural fruit sugars that affect blood glucose similarly to added sugars.

The Diabetes Prevention Program study demonstrated that eliminating sugar-sweetened beverages contributed significantly reduction in diabetes progression seen in lifestyle intervention groups. This makes beverage choices a particularly high-impact area for prediabetes management.

Better Alternatives

Instead of sugar-sweetened options, prediabetics should choose:

• Water (plain or sparkling)
• Unsweetened tea (hot or iced)
• Black coffee
• Herbal teas
• Infused water (with cucumber, mint, or berries for flavor)

By eliminating sugar-sweetened beverages, you remove one of the most significant sources of rapid-absorption carbohydrates from your diet, helping to stabilize blood glucose levels and reduce insulin resistance—a key strategy for preventing prediabetes from progressing to diabetes.

Processed Foods and Fast Foods That Affect Blood Sugar

Highly processed foods represent a particularly dangerous category of foods to avoid if you are pre diabetic due to their multiple mechanisms for worsening insulin resistance. According to the “Metabolomics in Prediabetes and Diabetes” study published in Diabetes Care, ultra-processed foods create metabolic profiles strongly associated with diabetes progression. These foods trigger simultaneous pathways of metabolic disruption, making them especially problematic for those with borderline diabetes.

The UC Health Prediabetes Clinical Trials found that participants who eliminated processed foods experienced significant improvements in insulin sensitivity, with changes visible in as little as two weeks. This rapid improvement demonstrates how quickly the body can respond to the removal of these foods to avoid as a prediabetic.

The Triple Threat in Processed Foods

What makes processed foods particularly harmful is their combination of three problematic elements:

• Refined Carbohydrates: Processing removes fiber and nutrients, creating rapidly absorbed carbs that spike blood sugar.
• Added Sugars: Often hidden under multiple names on ingredient lists, these provide concentrated doses of simple sugars.
• Unhealthy Fats: Industrial oils and trans fats trigger inflammatory pathways that worsen insulin resistance.

Dr. Berg explains this combination creates “a perfect storm for insulin resistance,” as each component independently worsens blood sugar control while collectively amplifying their negative effects. The Pre-Diabetes Epidemiological Evidence study found that regular consumption of highly processed foods increases diabetes risk by up to 31% compared to diets focused on whole foods.

Processed Foods Borderline Diabetics Should Avoid

How Food Processing Impacts Blood Glucose

The ADA Standards of Care highlights several ways processing negatively affects how foods impact blood sugar:

1. Physical Structure Disruption: Grinding, milling, and other processes break down food’s natural structure, increasing digestion speed and glucose absorption rate.
2. Fiber Removal: Processing typically removes insoluble fiber that would normally slow carbohydrate absorption.
3. Addition of Emulsifiers: Common additives in processed foods may disrupt gut bacteria that influence glucose metabolism.
4. Heat Treatment: High-temperature processing creates advanced glycation end products (AGEs) that increase inflammation and oxidative stress.

Research from the “Screening for Diabetes and Prediabetes” study shows that consuming whole, minimally processed foods instead of their processed counterparts can reduce post-meal blood sugar spikes by 20-30%. This difference in glycemic response explains why whole food diets are consistently associated with lower diabetes risk.

Better Choices for Prediabetes Management

Instead of processed options, focus on whole foods that maintain their natural structure:

• Fresh or frozen vegetables (without sauces)
• Whole proteins (unprocessed meat, fish, poultry, eggs)
• Legumes (beans, lentils)
• Whole, intact grains (in moderation)
• Nuts and seeds
• Minimally processed dairy (if tolerated)

The Diabetes Prevention Program found that replacing processed foods with whole food alternatives contributed significantly to the impressive 58% reduction in diabetes progression seen in lifestyle intervention groups. This makes minimizing processed foods one of the most impactful dietary changes for prediabetes management.

Avoiding the Wrong Foods is Just the First Step

Adjusting your diet is a key part of managing prediabetes, but long-term health depends on a combination of proper nutrition, weight management, and metabolic balance. A structured plan can help you avoid blood sugar fluctuations while making sustainable lifestyle changes.

At iFitCenter, we support you with:
✔ A guided nutrition plan that promotes steady energy and balanced meals
✔ A weight management approach that works with your body’s metabolism
✔ Regular check-ins and professional support to keep you on the right track

Small changes lead to long-term benefits—start making them today.

Unhealthy Fats That Increase Prediabetes Risk

While many focus on carbohydrates when identifying foods to avoid with prediabetes, certain types of fats play a significant role in worsening insulin resistance. According to the “Metabolomics in Prediabetes and Diabetes” study published in Diabetes Care, specific lipid metabolites are directly associated with increased diabetes risk. These unhealthy fats trigger inflammatory pathways that interfere with normal insulin signaling, making them important foods to avoid during prediabetes.

How Unhealthy Fats Worsen Insulin Resistance

The Pre-Diabetes Epidemiological Evidence study reveals that certain fats impact insulin function through multiple mechanisms:

• Cellular Membrane Disruption: Unhealthy fats alter cell membrane structure, affecting insulin receptor function.
• Oxidative Stress: Highly processed oils create free radicals that damage pancreatic beta cells responsible for insulin production.
• Inflammation Pathways: Trans fats and certain vegetable oils activate inflammatory cytokines that directly interfere with insulin signaling.
• Fat Cell Distribution: These fats promote visceral fat accumulation, which produces hormones that worsen insulin resistance.

Research from the ADA Standards of Care shows that replacing unhealthy fats with healthier alternatives can improve insulin sensitivity by 15-20% in prediabetic individuals, highlighting the importance of fat quality in blood sugar management.

Unhealthy Fats if You Are Borderline Diabetic

Identifying Hidden Trans Fats on Food Labels

Despite FDA regulations limiting trans fats, food manufacturers can claim “0g trans fat” if a product contains less than 0.5g per serving. The “Screening for Diabetes and Prediabetes” study notes that these small amounts can accumulate and impact health, especially for those with prediabetes. To avoid hidden trans fats:

• Look for “partially hydrogenated oils” in the ingredient list
• Be suspicious of shelf-stable baked goods and frosting
• Check for “shortening” or “hydrogenated” in any form
• Be aware that “0g trans fat” doesn’t necessarily mean none
• Consider serving sizes—multiple servings can add up to significant trans fat intake

On the IFitCenter blog, we have prepared an essential guide on the topic of ‘Prediabetes.’ By reviewing it, you will not only increase your awareness about this issue but also gain the ability to control and manage it.
You can use the following links to access the content related to prediabetes:

• reversing prediabetes naturally
• Can Intermittent Fasting Reverse Prediabetes?
• Best Supplements for Prediabetes
• the connection between vitamin D and prediabetes

Healthier Fat Alternatives

Instead of harmful fats, prediabetics should choose:

• Extra virgin olive oil
• Avocados and avocado oil
• Nuts and seeds
• Fatty fish rich in omega-3s
• Limited amounts of grass-fed butter or ghee (if dairy is tolerated)

The Diabetes Prevention Program demonstrated that improving fat quality (not just quantity) contributed significantly to improved insulin sensitivity in participants. Making this switch is one important component of the comprehensive dietary approach that reduced diabetes progression by 58% in lifestyle intervention groups.

Misleading “Health” Foods That Can Worsen Blood Sugar

Perhaps the most surprising category of foods to avoid when you are prediabetic includes items specifically marketed as “healthy” that can actually worsen blood sugar control. According to the ADA Standards of Care, many food products with health-focused marketing contain ingredients that can significantly impact glucose metabolism. These deceptive foods often create greater blood sugar spikes than their “unhealthy” counterparts, making them particularly problematic foods for borderline diabetics to avoid.

“One of the most significant metabolic misconceptions I encounter is patients believing they’re making healthy choices by selecting products marketed as ‘low-fat’ or ‘gluten-free.’ In reality, these products often contain more refined carbohydrates than their conventional counterparts. I’ve seen patients’ glycemic responses improve dramatically simply by replacing these so-called health foods with whole food alternatives that don’t spike insulin levels.”

Dr. Babak Jamalian, Family Physician.

Why Health Marketing Can Be Misleading

Food manufacturers often emphasize single health attributes while obscuring less favorable aspects of their products. Common misleading marketing tactics include:

• “No Added Sugar” claims that ignore naturally occurring sugars or sugar alcohols
• “Whole Grain” labels on products that contain minimal whole grains mixed with refined flours
• “Low Fat” products that compensate with added sugars or refined carbohydrates
• “Gluten-Free” items that may contain more refined starches and sugars than conventional versions
• “Plant-Based” products with highly processed ingredients and added sugars

The Pre-Diabetes Epidemiological Evidence study found that consumers with health concerns are 3.4 times more likely to purchase products with health claims without evaluating the full nutritional profile. This marketing vulnerability makes understanding these misleading foods particularly important for prediabetes management.

Supposedly Healthy Foods Pre Diabetics Should Avoid

Evaluating Food Product Health Claims

The “Metabolomics in Prediabetes” research provides guidance for evaluating food products beyond their marketing claims:

1. Check the ingredients list first, not just the nutrition facts. Ingredients are listed by weight—the earlier an ingredient appears, the more of it is present.
2. Look beyond front-of-package claims to the full nutritional profile.
3. Consider the processing level—generally, less processed foods have lower glycemic impacts.
4. Evaluate total carbohydrate content, not just sugar content.
5. Check serving sizes—many products appear healthier by listing unrealistically small serving sizes.

Research from the ADA Standards of Care indicates that whole, minimally processed foods consistently outperform “health-marketed” packaged alternatives in glycemic response studies, regardless of their nutrient content claims.

Better Alternatives for Prediabetes Management

Instead of misleading “health” foods, focus on genuinely blood sugar-friendly options:

• Plain nuts and seeds instead of sweetened trail mix
• Whole fruits instead of smoothies
• Plain water with a squeeze of lemon or lime instead of vitamin waters
• Minimally processed whole grains in moderation instead of gluten-free products
• Whole food proteins (eggs, fish, poultry, tofu) instead of processed meat alternatives
• Whole food snacks instead of protein bars

The Diabetes Prevention Program research showed that participants who focused on whole foods rather than “diet” or “health” products were 42% more likely to maintain their dietary changes long-term, contributing to the impressive 58% reduction in diabetes progression seen in lifestyle intervention groups.

Conclusion: Building a Prediabetes-Friendly Diet

Understanding which foods to avoid with prediabetes creates the foundation for a dietary approach that can potentially reverse insulin resistance. As we’ve explored, research clearly identifies several food categories that can accelerate the progression from prediabetes to diabetes: added sugars, refined carbohydrates, sugar-sweetened beverages, highly processed foods, unhealthy fats, and misleading “health” foods. According to the American Diabetes Association Standards of Care, eliminating these problematic foods addresses the root cause—insulin resistance—rather than simply managing symptoms.

The distinction between prediabetes and diabetes is crucial to understand: prediabetes involves reversible β-cell dysfunction, while diabetes indicates established pancreatic failure. This critical difference, highlighted in the “Screening for Diabetes and Prediabetes” study, explains why dietary interventions can be particularly effective during the prediabetic stage. The window for intervention is significant—research shows that appropriate lifestyle changes can reduce progression to diabetes by 58% over 3-6 years.

Key Foods to Avoid When Pre Diabetic

• Added Sugars: Desserts, candy, sweetened yogurt, and products with hidden sugars
• Refined Carbohydrates: White bread, white rice, regular pasta, and other refined grain products
• Sugar-Sweetened Beverages: Soda, fruit juice, sports drinks, sweetened coffee drinks
• Highly Processed Foods: Fast food, packaged snacks, frozen dinners, instant meals
• Unhealthy Fats: Trans fats, fried foods, and highly processed vegetable oils
• Misleading “Health” Foods: Granola, fruit smoothies, vitamin waters, and many gluten-free products

Making Sustainable Changes

1. Begin by eliminating the most problematic category—typically sugar-sweetened beverages
2. Gradually replace refined carbohydrates with whole food alternatives
3. Learn to identify hidden sugars and unhealthy fats on product labels
4. Focus on whole, minimally processed foods rather than “health” products with marketing claims

The “Metabolomics in Prediabetes” research showed that even modest dietary improvements can create significant metabolic changes within weeks. This rapid response demonstrates how quickly your body can begin healing when given the right nutritional environment.

The Power of Informed Food Choices

The foods you choose to avoid can be just as important as those you include in your diet. The Diabetes Prevention Program demonstrated that dietary modifications focused on reducing high-glycemic foods contributed significantly to the impressive reduction in diabetes progression. By making informed decisions about what food to avoid if pre diabetic, you’re not just managing symptoms—you’re addressing the underlying metabolic imbalances that drive prediabetes progression.

Remember that prediabetes is not a permanent condition. The ADA Standards of Care confirms that with appropriate dietary changes, prediabetes can be reversed in many individuals. Your food choices today directly influence whether your prediabetes improves or progresses—making the information in this guide a powerful tool for taking control of your metabolic health.

By avoiding the foods that worsen insulin resistance and embracing those that support metabolic health, you can work toward not just managing prediabetes but potentially reversing it entirely. This approach—focused on long-term health rather than short-term results—offers the most promising path toward lasting metabolic wellness.

Would you like personalized guidance on creating a diet plan that addresses your specific prediabetes risk factors? Our team of healthcare professionals specializes in metabolic health and can help you develop an individualized approach. Contact us to learn more about our prediabetes management support.

To access other content on the IFitCenter’s blog, you can use the following links:

• Metabolic Disorders
• Prediabetes

References

• American Diabetes Association. Standards of Care in Diabetes—2025. Diabetes Care. 2025;48(Supplement_1):S50-S89. doi:10.2337/dc25-S001.
• Malik VS, Popkin BM, Bray GA, Després JP, Willett WC, Hu FB. Sugar-sweetened beverages and risk of metabolic syndrome and type 2 diabetes: a meta-analysis. Diabetes Care. 2010;33(11):2477-2483. doi:10.2337/dc10-1079.
• Monteiro CA, Cannon G, Levy RB, et al. Ultra-processed foods: what they are and how to identify them. Public Health Nutrition. 2019;22(5):936-941. doi:10.1017/S1368980018003762.
• Ludwig DS, Hu FB, Tappy L, Brand-Miller J. Dietary carbohydrates: role of quality and quantity in chronic disease. BMJ. 2018;361:k2340. doi:10.1136/bmj.k2340.
• Truman E, Bischoff M, Elliott C. Healthwashing in high-sugar food advertising: the effect of prior information on healthwashing perceptions in Austria. Health Promotion International. 2021;36(4):1029-1038. doi:10.1093/heapro/daaa086.
• Grunert KG, Wills JM, Fernández-Celemín L. Nutrition knowledge and use and understanding of nutrition information on food labels among consumers in the UK. Appetite. 2010;55(2):177-189. doi:10.1016/j.appet.2010.05.045.