What exactly is the Glycaemic Index (GI)?

A definition

The Glycaemic Index is a scale which ranks foods based on the effect they have on blood sugar levels. It measures how fast a carbohydrate  gets into 

diabetes diagram

a person’s blood as sugar.The higher the index, the less healthy the carbohydrate.


How does it work?

The Glycaemic Index runs from 0 to 100 and uses glucose – which has a GI value of 100 – as the reference. The effect other foods have on blood sugar levels are then compared to this scale. In simple terms the GI tells us whether a food raises blood sugar levels dramatically, moderately or a little bit.


What does this mean for my eating habits? 

Foods with a low GI value slowly release sugar into the blood, providing you with a steady supply of energy, leaving you satisfied for longer and less inclined to snack. In contrast, foods with a high GI value cause a rapid – but short-lived – rise in blood sugar. This effect leaves you lacking in energy, feeling hungry within a short time and more likely to reach for a snack.



LowFoods usually have a rating of GI 55 or less
MediumFoods have a rating of GI 56-69
High – Foods with a GI of 70 or more


Test your foods for their glycemicx index level 


The science

Low GI diets are useful for those with diabetes, although the GI is not a sufficient reason to include or exclude a food. For example, tropical fruits have a higher GI than fruits like apples or oranges, but tropical fruits are such great sources of many nutrients that they should never be excluded from a diet for those with diabetes. Also, many low GI foods such as chocolate spread or high sugar cereals are not suitable for those with diabetes.

There is no evidence from long-term studies that low GI diets are useful for weight loss. After reviewing the evidence carefully, the US Dietary Guidelines (2010) concluded that “strong and consistent evidence shows that glycaemic index and/or glycaemic load are not associated with body weight and do not lead to greater weight loss or better weight maintenance”. Rosemary Stanton 


What is diabetes?

Diabetes symptoms cartoon


Diabetes can be thought of as a disease caused by the body’s inability to process carbohydrates properly. Insulin, a hormone produced by the pancreas, enables the body’s cells to absorb glucose (blood sugar). In people with diabetes, the cells don’t respond properly to insulin. In some cases, the body doesn’t produce any or enough insulin to properly manage blood sugar levels. For many with type 2 diabetes, neither process works properly.


GI and Diabetes
Although the GI of foods is important for all people, diabetics need to monitor their sugar levels as the disease is one where the body does not convert sugar into energy efficiently.


Watch food label ingredients.  These are some of the names for sugar you may find in the ingredients list: bakers sugar, brown sugar, cane sugar, caster sugar, coconut sugar, confectioners sugar, crystals, dextran, dextrin, dextrose, diastatic malt, fructose, galactose, glucose, glucose solids, granulated sugar, maltose, raw sugar, refiners syrup, sugar cubes, superfine sugar, table sugar,white sugar, yellow sugar.



 Make the low GI choice


 Some websites for further information:

If you are looking for fun and games related to food, refer to our Families Food section.