What is Glycemic Index? Why it is relevant for Diabetics?

Those with diabetes know that a proper diet is essential for controlling the disease. Many foods can cause a sudden rise in blood sugar levels. Carbohydrates such as bread and refined sugar are easy for the body to metabolize and turn into glucose. Glucose is the fuel that the body uses for energy. Sudden spurts in the blood sugar level can make the diabetic patient’s condition worse. An excess of these easily digested carbs will make it impossible to control blood sugar levels, even with insulin and other diabetes medications. The carbs found in whole grains and vegetables are less easy to digest and so the rise in glucose level is gradual and not as great, making these foods a lot safer for diabetics. The glycemic index is a method that allows patients to differentiate between the dangerous “fast” carbs and the safer “slow” ones. It is an essential tool for diabetics to control their blood sugar levels.

What Is the Index?

The glycemic index is a numbered scale that is used to evaluate how fast certain carbs are converted into glucose by the body. This is very important because while diabetics know the importance of controlling carb intake, the carbs in different foods may be absorbed by the body at different speeds. The lower the glycemic index, the lesser the impact of the food on blood sugar levels. Generally, the glycemic categorization is as follows:

  • A value below 55 = low impact
  • A value between 56 – 69 = medium impact
  • A value above 70 = high impact

Generally, foods that require the least cooking/preparation tend to have a lower glycemic index than refined and processed food items.

The Index Is Not Set in Stone

The glycemic index is not something to follow or accept blindly. The values can change, often significantly. 4 main factors affect the index and the impact food can have on glucose levels.

  1. The way the food is prepared can raise or lower the index. For example, using vinegar, lemon juice or other acidic substances in the cooking process can lower the index.
  2. As certain fruits like bananas ripen, the glycemic index rises. Being aware of the index enables you to find the right balance between the benefits of consuming fruits and the risks.
  3. The right combination of foods can keep the index at the right level. Combining high index foods with low index ones will create an average index value that will keep blood sugar levels from spiking.
  4. Your overall physical condition including how much you exercise, whether you have any other medical disorders and certain genetic factors can also affect the pace at which carbs are absorbed by the body.

Beyond the Index

The glycemic index should not be the only factor in deciding what foods you should eat. Common sense and a basic understanding of nutrition are also important. A low glycemic index does not mean that a food is super healthy. Calorific value, vitamin content and minerals are all important constituents of healthy food. Potato chips are a good example of this. The glycemic index of potato chips is about the same as green peas and oatmeal. However, both peas and oatmeal are healthier options because they have more nutrients.

The other factor to consider is the amount you eat – the portion or helping size. The greater the quantity, the more the carbs. This is known as the glycemic load. Packaged foods that list the glycemic index usually also mention the glycemic load. In other words, the index is for a specific quantity of food. Eating very large amounts of low glycemic value foods will cause blood sugar levels to rise, often beyond safe limits.

When buying packaged foods check to see if the labels state the glycemic index. Buying those with the lowest value is always better. You can also search online for the glycemic index of the foods you consume and modify your diet according to the values. If in doubt, consult your doctor or a dietician or nutrition counselor.

Advances in medicine mean that those with diabetes can now live active and comfortable lives. However, medication and insulin are not enough. Controlling your diet using the glycemic index is a key factor in maintaining the required blood sugar levels.


Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai, Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.

Chennai – 044 4000 6000 • Trichy – Cantonment – 0431 4077777 • Trichy – Heartcity – 0431 4003500 • Trichy – Tennur – 0431 4022555 • Hosur – 04344 272727 • Salem – 0427 2677777 • Tirunelveli – 0462 4006000 • Bengaluru – 080 6801 6801

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