What is Glycemic Index?

Diabetes management calls for a major overhauling in the dietary practices of an individual. The most important nutrient to be modified is carbohydrate. Let us see how and in what way knowing GI of a particular food helps?

Carbohydrates are a class of foods which are known for their saccharide (sugar) content. A food containing carbohydrate which when digested and absorbed increases the glucose levels of blood. This increase in blood glucose has now become the key to planning diets for diabetics, obese and weight watchers. The term used to describe this increase in blood glucose is called as Glycemic Index (GI).

The concept of GI was developed by Dr David J. Jenkins and his colleagues in 1980–81. Glycemic index consists of a scale from 1 to 100, indicating the rate at which 50 grams of carbohydrate in a particular food is absorbed into the blood. On this scale, Glucose is used as the main reference point and is rated 100. A GI value of 70 and above indicates High Glycemic index, 56-69 medium and less than 55 indicates low GI. Simply put a food which does not lead to a sharp increase in blood sugar post absorption is termed as a low GI food. Thus the foods which take time to digest and slowly get absorbed in blood have a low GI and vice versa.

So if you are trying to manage your blood sugar or trying to lose weight select foods with Low Glycemic index as they will cause a slower rise in blood sugar. Foods with a low glycemic index tend to have more fibre than the higher glycemic index foods. In other words, select dense wholegrain cereals, brown rice, whole-wheat pasta, dalia, rather than refined or processed white bread, white rice and pasta.

Apart from knowing the GI value of foods, there are other factors which can help us in managing our blood glucose in a better way. These include:

  1. Even distribution of carbohydrate over the day rather than loading a meal completely with carbs.
  2. Eating small frequent meals rather than 2-3 large meals.
  3. Various forms of carbohydrate affect blood glucose levels in different ways even though the carbohydrate content is the same. E.g., a) Physical form – solid, liquid: a liquid food is easier to digest and thus increases blood sugar suddenly. Solids taking more time in digesting and thus have a high GI. e.g. A fruit Vs fruit juice. b) Raw or Cooked: raw carbohydrate foods rather than cooked ones are more slowly absorbed. c) Whole-foods rather than processed foods are more slowly absorbed.
  4. Some of the complex carbohydrates do behave more like simple sugars, with a quick release of glucose. Like potatoes and many breakfast cereals such as cornflakes, all have a high GI.

Following is a Chart of few commonly consumed foods with their GI:

Food ProductGlycemic Index
Rice, brown50
Rice, white58
Buckwheat (kuttu)54
Kellogg’s Corn Flakes92
Kellogg’s Special K69
White bread70
Potato, baked85
Potato, boiled88
Sweet Corn60
Sweet Potato61
Yam (Zimikand)37
Broad Beans79
Soy bean18
Apple Juice40
Coca Cola63
Orange Juice52
Table Sugar68


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