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Can we control blood sugar with food? Let's talk about the Glycemic Index (GI)!

MBBS
Medically Reviewed by MBBS ✓ Medically Reviewed
📅 Updated: Jul 14, 2026 • ⏱ 7 min read • Editorial policy
Can we control blood sugar with food? Let's talk about the Glycemic Index (GI)!
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When we talk about food, especially when we think about things like diabetes and weight loss, we often hear the word 'carbohydrate'. But are all carbohydrates the same? Think about it, eating rice and eating chickpeas both contain carbohydrates. But the way they affect our bodies is very different. Today we are going to talk about a measurement that will help us understand exactly that difference. It is called the Glycemic Index , or GI for short as we all know it.

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Simply put, what is the Glycemic Index (GI)?

Very simple. The Glycemic Index (GI) is a measure of how quickly a carbohydrate-containing food is converted into glucose, or "sugar" as we know it, and added to the blood after we eat it.

Think of it like you're filling a car with gasoline. Some types of gasoline burn quickly and give the car instant power. Some burn slowly and give it power for a long time. That's how this food is.

The GI value is measured on a scale from 1 to 100.

  • Foods with a high GI (70 or higher) are digested quickly and cause a rapid rise in blood sugar levels.
  • Foods with a low GI (55 or less) are digested slowly, helping to keep blood sugar levels stable and stable.

Knowing this GI value will be very useful for you, especially if you are a person with diabetes or trying to control your weight.

Our body produces a hormone called insulin, which uses the sugar in our blood to provide energy to our cells. When blood sugar levels suddenly rise, insulin has to do a lot of work. This can be difficult for someone with diabetes to control. Therefore, choosing foods with a low GI value can help control this condition.

What foods have low, medium and high GI values?

Okay, now let's see what these low, medium, and high GI foods are. You can get a good idea by looking at this table.

Foods with a low GI value (55 or less) Foods with a medium GI value (56 - 69) Foods with a high GI (70 or higher)
Many green vegetables, fruits like apples, oranges, pears, raw carrots, chickpeas, lentils, cowpeas, green beans, peanuts, cashews, non-fat milk. Corn, banana, pineapple, plum, cherry, oats, brown rice, honey, kurakkan bread. White rice, bread, potatoes, sweet cakes, donuts, cantaloupe, jelly beans, cornflakes.
Meaning: These are digested slowly. Blood sugar rises slowly. Meaning: These are digested at a moderate rate. Meaning: These are digested very quickly. They cause a rapid rise in blood sugar.

Can the GI value of a food change?

Yes, it can. The GI value on a food label doesn't always affect our bodies in the same way. There are several reasons for that.

  • Cooking method: Starchy foods (e.g. pasta, potatoes) increase in GI when cooked. Similarly, adding oil, fiber, or an acidic ingredient like lemon or vinegar to the food lowers the GI.
  • Ripeness: When a fruit, for example a banana, is fully ripe, its sweetness increases and its GI value also increases.
  • Pairing foods: When you eat rice, which has a high GI value, and then add something high in protein and fiber, such as lentils, vegetables, or fish, which have a low GI value, the GI value of the entire meal decreases.

Difference between Glycemic Index (GI) and Glycemic Load (GL)

Another term we hear when talking about GI is Glycemic Load (GL) . There is a slight difference between the two.

Simply put:

  • GI (Glycemic Index) only refers to the speed at which a food turns into sugar in the blood. It is the "quality" of the food.
  • GL (Glycemic Load) refers to how the quantity of a food you eat affects your blood sugar.

Let's look at an example: Watermelon has a relatively high GI. But since the amount of carbohydrates in a slice of watermelon that we usually eat is low, it has a low GL. That means that eating a slice of watermelon doesn't have a big impact on blood sugar.

However, if you buy a donut, its GI value is also high, and since it contains a lot of sugar and refined flour, its GL value is also very high.

This means that the type of food you eat is just as important as the amount you eat. Even a food with a high GI value can have a very small effect if consumed in very small amounts.

Benefits of a low GI diet

By adopting a low GI diet, you can gain the following benefits:

  • Helping to control or reduce weight.
  • Helping to lower blood pressure.
  • Reducing cholesterol levels.
  • Helping to control or reduce the risk of diabetes.
  • Reducing the risk of heart disease.

But remember one thing. The GI value is not the only factor to consider when choosing a healthy food. Just because a food has a low GI value does not make it 100% healthy. For example, potato chips may have a lower GI value than oats. However, oats are much higher in nutritional value. Therefore, it is very important to consider the vitamins, minerals, and calories they contain when choosing a food.

If you want to know more about this, it's best to talk to your doctor . He or she can give you the best advice based on your health condition.

💡 Take-Home Message

  • The Glycemic Index (GI) is a measure of how quickly a carbohydrate food you eat raises your blood sugar levels.
  • Low GI foods (vegetables, peas, lentils) control blood sugar levels, while high GI foods (white rice, bread, sugar) raise it quickly.
  • Don't just look at the GI value. Also consider the nutritional value of the food and the portion size you eat. The Glycemic Load (GL) measurement is important for this.
  • The overall GI value of a meal can be changed by factors such as how the food is cooked and how it is mixed with other foods.
  • Always consult your doctor before making any changes to your diet, especially if you have a medical condition such as diabetes.
❓ FAQ

FAQ

Evidence-based clinical answers to common patient questions

Can the GI value of a food change?

Yes, it can. The GI value on a food label doesn't always affect our bodies in the same way. There are several reasons for that.

  • Cooking method: Starchy foods (e.g. pasta, potatoes) increase in GI when cooked. Similarly, adding oil, fiber, or an acidic ingredient like lemon or vinegar to the food lowers the GI.
  • Ripeness: When a fruit, for example a banana, is fully ripe, its sweetness increases and its GI value also increases.
  • Pairing foods: When you eat rice, which has a high GI value, and then add something high in protein and fiber, such as lentils, vegetables, or fish, which have a low GI value, the GI value of the entire meal decreases.
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⚠️ Important: Medical articles and information on Nirogi Lanka are strictly for educational and awareness purposes and do not substitute professional medical advice, diagnosis, or treatment. Always consult a qualified physician for any medical concerns.