Glycaemic index

All carbohydrates will break down into glucose in the bloodstream and raise blood glucose. How much they raise blood glucose will depend on how quickly they break down to glucose. This concept of how fast food breaks down into glucose is called glycaemic index (GI).

The food that breaks down the fastest into glucose in the bloodstream is glucose itself. Since it’s super quick, it’s given a score of 100. Every other food is then compared to glucose and given a score out of 100 which is determined by measuring the effect of the food on the resultant blood glucose in the bloodstream.

The lower the score (less than 55), the slower the food will break down into blood glucose. A slower release is optimal because it will give insulin time to respond to the blood glucose in the bloodstream and ensure it doesn’t sit too long in the bloodstream.

A rapid breakdown of food into glucose (high-GI) will mean a fast increase of blood glucose and the insulin may not be able to respond optimally to the glucose spike, meaning that the glucose will sit too long in the bloodstream and start causing damage in the blood vessels. If this happens too often it can cause diabetes complications in the large blood vessels (heart) and smaller vessels (kidney, eyes and feet).

Glycaemic Index FOODS

LOW-GI (<55) MEDIUM-GI (56-69) HIGH-GI (70>)


Rice bran








Low-fat yoghurt







Bran cereal 42 Broccoli 15 Plain yoghurt 14 Beans, dried 40
Spaghetti 42 Celery 15 Whole milk 27 Lentils 41
Sweet corn 54 Cucumber 15 Soya milk 30 Kidney beans 41
White rice 64 Lettuce 15 Fat-free milk 32 Split peas 45
Couscous 65 Peppers 15 Skim milk 32 Lima beans 46
Wholewheat bread 71 Spinach 15 Chocolate milk 35 Chickpeas 47
Muesli 80 Tomatoes 15 Fruit yoghurt 36 Pinto beans 55


85 Cooked 


39 Ice cream 61 Black-eyed beans 59
Oatmeal 87
Taco shells 97
White bread 100
Bagel, white 103
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