Foods to Avoid with Diabetes and Prediabetes (Impaired Glucose Tolerance)

Almost 30 million Americans are diabetic which accounts for close to 10% of the population. Out of these cases, approximately 8 million people who are diabetic do not know that they have diabetes. With diabetes becoming more prevalent, it is important that every person avoid the risk factors that contribute to this disease. Foods play an important role, not only in contributing to conditions like obesity that increase the risk of diabetes, but also to the management of diabetes.

How does food affect diabetes?

Diabetes is a condition where the pancreas has a deficiency of insulin (type 1 diabetes) or the body becomes unresponsive to insulin (type 2 diabetes). Insulin helps to control the blood glucose levels. When these levels rise above the normal range, insulin is secreted by the pancreas into the bloodstream. It stimulates the liver to convert glucose into glycogen (a storage form of glucose) and increases the uptake of glucose by the cells, among other effects that lowers blood glucose levels or slows down the rise of these levels.

Therefore in diabetes the body is unable to control glucose levels within the narrow range that is considered normal. Elevated blood glucose levels can damage cells, tissues and organs throughout the body over time. It can even cause acute diabetes-related complications which may be life threatening. While diabetes is a problem with the pancreas and insulin, foods and beverages do play a role in the blood glucose levels.

Food is broken down in the gastrointestinal tract. This is both a chemical and mechanical process mediated by digestive enzymes and the strong muscle contractions of the gut wall, respectively. Once foods are broken down into simpler substances, these nutrients are then absorbed into the bloodstream from the gut. Certain foods and beverages cause a rapid rise in the blood glucose levels and in diabetes the body may not be able to cope accordingly.

List of Foods to Avoid

A diabetes diet should be balanced, restricted in calories and comprise of low glycemic index (GI) foods. A balanced diet ensures that the body is deriving sufficient nutrition without the risk of deficiencies. By restricting calories, the body is not overwhemed with nutrients that may not only cause a rise in glucose levels but also contribute to obesity which further impairs glucose control.

However, for many diabetics the focus is on the glycemic index of foods. The glycemic index is a scale whereby foods are classified according to its ability to raise blood glucose levels over a period of time. High glycemic index (GI) foods raise the blood glucose levels faster than moderate to low glycemic index (GI) foods. Therefore diabetics should avoid high GI foods as far as possible but it may sometimes be acceptable depending on the glycemic load per serving.

Read more on worst foods for diabetics.

The list of foods discussed below is a general guideline. Always consult with a registered dietitian for nutritional advice and an individualized eating plan. Sometimes foods and beverages that may be considered suitable for diabetics are still a problem for certain individuals. Regular monitoring of blood glucose levels will assist diabetics in identifying these problem foods and drinks, which should then be avoided.

People who have been diagnosed with prediabetes or impaired glucose tolerance (IGT) should also avoid the foods and drinks discussed below. This may help to prevent the development of diabetes and even reverse prediabetes in some cases. Remember that even non-diabetics can benefit from an eating plan that is for diabetics. This may help with maintaining a healthy body weight and at times even reduce the risk of developing diabetes.


Breads, rice, pasta, grains and potatoes are often considered as the main starches although this may vary to some degree by country and region.

  • Most breads – white, brown and wholewheat – should be avoided. This includes homemade breads, bagels, tortillas, rolls and buns. Wholegrain, rye and breads marked low GI are a better choice in moderation.
  • White rice should be avoided or eaten in small quantities. Long grain white rice like basmati rice and brown rice are better options but only to a slight degree.
  • Pasta made from white flour should be avoided while wholewheat or durum wheat flour pasta is a better choice.
  • Processed or refined grains should be avoided. Wholegrains, including millet, oatmeal and quinoa, are a better option. Avoid grains with added sugar, such as breakfast cereal with added sugar and little wholegrain.
  • Potatoes that are baked, boiled or steamed are a better choice than fried potatoes, including french fries. However, the quantity is of potato is equally important.


  • Avoid red meat as far as possible but if small amounts are to be eaten then it must be lean cuts.
  • Fish, chicken and other poultry are the better choice. Ensure that meat servings are skinless and lean.
  • Avoid full cream or full fat dairy. Low fat dairy is the better option but portions must be small.
  • Beans, nuts, seeds or tofu are suitable plant-based protein sources for diabetics.
  • Processed meats, cured meats and meats cooked with lard or fried must be avoided.

Fruit and Vegetables

  • Fresh fruit that is eaten raw in moderation is usually not a problem.
  • Canned, sugared and juiced fruits should be avoided.
  • All fresh vegetables are acceptable when consumed in moderation and prepared by steaming, boiling or roasting without butter. Frozen vegetables are also acceptable.
  • Avoid canned and pickled vegetables and do not prepare vegetables with cream, sauces or butter.

Processed Foods

As far as possible, processed foods should be avoided. A range of additives are included in these foods. Apart from hidden salts, there may also be hidden sugars which do not contribute to a pronounced sweet taste but can rapidly raise blood glucose levels. Rather prepare fresh foods at home where all the ingredients in a meal are known. Fast foods should also be avoided as these foods are often high in carbohydrates and laden with sugar and fats.

Sugary Foods and Drinks

Foods and drinks with added sugar should be avoided altogether. Even small quantities can have a significant effect on blood glucose leves. This includes sodas, fruit juices, tea or coffee with sugar and other drinks as well as confectionaries such as cakes, cookies and pastries. Apart from the sugar, some of these foods and drinks are made of other ingredients that may not taste sweet but can also increase blood glucose levels, for example white flour. Rather opt for diabetic-friendly foods, including drinks and treats.

Read more on foods with high sugar content.

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