What is the glycemic index and why does it matter?
The glycemic index (GI) is a number from 0 to 100 that shows how quickly a carbohydrate-containing food raises blood sugar compared with pure glucose, which is given a value of 100. High-GI foods are digested quickly and cause a sharp rise in blood sugar. Low-GI foods are digested more slowly and cause a gentler, steadier rise. For people with diabetes or prediabetes, fewer sharp spikes after meals makes blood sugar easier to manage.
Key takeaways
- GI is grouped as low (55 or less), medium (56 to 69) and high (70 or more).
- Dals, chana, rajma and most whole fruits are low GI. White rice, potatoes and refined flour (maida) are usually high GI. Whole wheat roti and brown rice are closer to medium.
- How much you eat matters as much as what you eat. This is called glycemic load.
- Pairing carbohydrates with dal, curd, paneer or vegetables lowers the overall effect of a meal on blood sugar.
GI is a useful guide, but it is not a measure of how healthy a food is. A food can be low GI and still be high in calories or unhealthy fats, so GI works best alongside portion size and overall diet quality. In Indian kitchens, the same food can also have quite different GI values depending on the grain variety, how it is processed and how it is cooked.
How is the glycemic index measured?
To measure GI, researchers give a small group of healthy volunteers a portion of the test food containing a fixed amount of carbohydrate, usually 50 grams. Their blood sugar is checked several times over the next two hours and compared with their response to the same amount of pure glucose. The result, expressed as a percentage of the glucose response, is the food’s GI.
Because the result depends on the exact food and recipe tested, published GI values for the same dish can vary quite a bit. Think of any GI number as an approximate guide rather than an exact figure.
What changes the GI of a food in Indian kitchens
- Processing. Finely milled flours such as maida, and grains with the bran removed, are digested faster than whole grains and have a higher GI.
- Cooking time. Overcooked, very soft rice or dalia is digested faster than grains cooked just until done.
- Ripeness. A ripe banana or mango raises blood sugar faster than a less ripe one.
- What it is eaten with. Protein, fibre and some fat slow down digestion, so rice with dal and sabzi has a smaller effect than plain rice on its own.
Glycemic index of common Indian foods
The table below gives approximate ranges based on published GI tables and studies. Actual values vary with variety, recipe and portion, so use this as a rough guide.
| Food | Approximate GI | Category |
|---|---|---|
| Chana (chickpeas), boiled | about 30 | Low |
| Rajma (kidney beans), boiled | about 25 to 35 | Low |
| Whole moong and other dals | about 25 to 45 | Low |
| Apple, guava, orange (whole fruit) | about 35 to 45 | Low |
| Plain curd and milk | about 30 to 40 | Low |
| Banana (ripe), mango (ripe) | about 50 to 60 | Low to medium |
| Whole wheat roti (chapati) | about 55 to 65 | Medium |
| Brown rice | about 60 to 70 | Medium |
| Sweet potato, boiled | about 60 to 65 | Medium |
| Idli, dosa, poha | about 60 to 75 | Medium to high |
| White rice, steamed | about 70 to 80 | High |
| Potato, boiled | about 75 to 85 | High |
| Maida products (white bread, naan) | about 70 to 75 | High |
| Sugar, jaggery, glucose drinks | high | High |
A common myth is that jaggery or honey is safe in diabetes because it is “natural”. Both raise blood sugar in much the same way as sugar, so treat them the same way.
Glycemic load: why portion size matters
GI tells you how fast a food raises blood sugar, but not how much carbohydrate you are actually eating. Glycemic load (GL) takes both into account. A small bowl of a medium-GI food can have less effect than a large plate of a low-GI food.
For example, watermelon has a high GI, but a small slice contains little carbohydrate, so its effect is modest. On the other hand, a large heap of brown rice can still push blood sugar up, even though brown rice is a better choice than white rice. In everyday terms: choose lower-GI foods, and keep portions of any rice, roti or other grain moderate.
How to choose lower-GI options in everyday Indian meals
You do not need to give up familiar dishes. Small swaps make a real difference:
- Build your plate. Fill half the plate with non-starchy vegetables and salad, a quarter with dal, chana, paneer, curd, eggs or fish, and a quarter with rice or roti.
- Add dal or legumes to grains. Dal-chawal, khichdi with extra dal and vegetables, or rajma with a small portion of rice all have a gentler effect than rice alone.
- Prefer less-processed grains. Whole wheat over maida, whole or broken wheat over refined products, and whole grains such as millets in moderate portions.
- Use besan and moong. Besan chilla or moong dal chilla with vegetables is a lower-GI breakfast than poha or white bread.
- Eat whole fruit, not juice. Whole fruit contains fibre that slows the rise in blood sugar. Juice, even fresh and without added sugar, raises it faster.
- Eat vegetables and protein first. Starting the meal with salad, sabzi or dal before the rice or roti can soften the rise in blood sugar after the meal.
Some practical examples:
- Breakfast: moong dal chilla with grated vegetables and a bowl of plain curd.
- Lunch: two phulkas, a bowl of dal, a large serving of sabzi and cucumber-tomato salad.
- Dinner: a small portion of rice with rajma or chana and a vegetable dish.
For more meal ideas, see our Indian diabetes diet chart and our practical diabetes management tips.
Festivals and fasting
Festivals often bring sweets, fried snacks and bigger meals. A few simple habits help:
- Keep sweets small. Have a small piece after a meal rather than on an empty stomach, and fill the rest of the plate with salad, sprouts or roasted chana.
- Watch farali foods. Sabudana, potato and rajgira or kuttu puris can raise blood sugar quickly. Keep portions small and add curd, peanuts or paneer.
- Choose unsweetened drinks. Water or plain buttermilk instead of sweetened drinks or juices.
- Check your sugar more often around festive meals if you monitor at home, to see how different foods affect you.
Important: if you take insulin or tablets that can cause low blood sugar (such as sulfonylureas), fasting can be risky. Speak to your doctor before a fast so your medicines can be planned safely. Do not change your medicine doses on your own.
When to see an endocrinologist
See an endocrinologist if your blood sugar stays high despite diet changes, if you have frequent low sugar episodes, or if you have symptoms such as excessive thirst, frequent urination, blurred vision or slow wound healing. Even if things seem stable, a review can help fine-tune your treatment and diet and reduce the risk of long-term complications.
At Vishuddha Endocrine Clinic, Dr. Moxit Shah can review your glucose readings, your usual meals and your medicines together, and help you build an eating pattern that suits Indian food habits. Useful things to bring or ask about:
- Your recent blood sugar readings or CGM report, and your latest HbA1c.
- Which foods you notice cause the biggest rise.
- How to plan meals and medicines around festivals, fasts, travel or work shifts.
Frequently asked questions
What does a low glycemic index mean?
A low GI (55 or less) means the food’s carbohydrate is digested and absorbed slowly, so blood sugar rises gradually rather than spiking.
Can I eat rice if I have diabetes?
Many people with diabetes can include some rice. Keep the portion small, eat it with dal, vegetables and a protein source, and check how your sugar responds. Brown rice is a better choice than white rice, but portion size still matters.
Is jaggery or honey better than sugar for diabetes?
Not meaningfully. Jaggery and honey raise blood sugar much like sugar does, so they should be limited in the same way.
Do all fruits have a low GI?
No. Apples, guava, oranges and pears are low GI. Ripe bananas, mangoes, chikoo and grapes are higher. Whole fruit in moderate portions is better than juice.
Is GI the only thing to consider?
No. Portion size, total calories, fibre, protein and overall diet quality all matter. GI is one helpful tool, not a complete diet plan.
Need personalised advice? Book a consultation with Dr. Moxit Shah at Vishuddha Endocrine Clinic, Ahmedabad. Book an appointment or call +91 99799 92797.
This article is for general education and does not replace a consultation. Please speak to your doctor before making any change to your treatment.
