Glycaemic Index

By : Ms Ng Hui Ting, Pharmacist at Unity Tampines One

First seen in Lifestyle Magazine (June 2013), pg 67. This article is an unbreached version of the print edition.

Glycaemic Index: What you need to know?

Are you having difficulties controlling your blood glucose levels? Eating a balanced and healthy diet is the cornerstone to diabetes control. The food that we take contains mainly of carbohydrates, fats, protein and fibre. Carbohydrates are converted to glucose in our body, and glucose is the main source of energy for our daily activities. However, some food can cause the blood glucose levels in the body to rise faster than others. Hence, for proper glucose control, the type of carbohydrates taken is important. One way of selecting the suitable type carbohydrates is the use of Glycaemic Index.

What is Glycaemic Index (GI)?

A measure of how fast the blood glucose level rise after eating a particular type of food (that contains carbohydrates).

Gives an estimate of how much a gram of carbohydrate raises a person’s blood glucose level after eating, as compared to consumption of pure glucose.

It is ranked on a scale of 0 to 100, using glucose as the reference food. Glucose has a glycaemic index of 100.

The GI index only ranks food containing carbohydrates (e.g. rice, juice); hence meat, fish, and poultry do not have GI.

How is food ranked accordingly to GI?

Carbohydrates are ranked into high or low GI.

High GI food:

Contains carbohydrates that are digested and absorbed rapidly into the bloodstream.

Raises blood glucose level quickly 2 hours after consumption.

Suitable for fast energy recovery and people who are hypoglycaemic (low blood glucose levels).

Have a value of 70 and above.

Examples of high GI food:



White bread




French fries




White rice, steamed


Low GI food:

Contains carbohydrates that break down slowly and absorbed gradually into the bloodstream.

Raises the blood glucose level less quickly 2 hours after consumption.

Gives better long-term blood glucose control.

May protect against diabetes or cardiovascular diseases in healthy people.

Have a value of 55 or less.

Examples of low GI food:



Roasted and salted peanuts


Low-fat yoghurt with sweetener


Whole milk


Skimmed milk


Low-fat fruit yoghurt


Orange juice


Baked beans in tomato sauce


Milk chocolate




Low GI food is recommended for good blood glucose control. If the meal contains high GI food, it is recommended to switch or eat them together with a lower GI food. However, GI serves only as a guide and should not be used as the only factor during food selection. Having a balanced diet that contains the right proportion of fats, carbohydrates, protein and fibre is still the main key for a healthy glucose control.


Health Promotion Board - Diet and Diabetes:

About Glycaemic Index:

Glycaemic Index and Diabetes - American Diabetes Association:

Wikipedia – Glycaemic Index: