Glycaemic Index (GI)
The Glycaemic Index (GI) is a way of describing how quickly carbohydrate-containing foods raise blood glucose levels after eating.
What are Carbohydrates?
Foods with a high GI are broken down into glucose and absorbed more quickly, resulting in a faster rise in blood glucose levels. Foods with a low GI are absorbed more slowly, providing a more gradual and sustained release of glucose into the bloodstream over time.
Understanding the difference between high and low GI carbohydrates can help people make informed food choices for different situations, including everyday energy needs, physical activity, travel, sport, and carbohydrate planning.
For most day-to-day situations, lower GI carbohydrates are often recommended as part of a balanced diet, as they are digested more slowly and may help support steadier energy levels and blood glucose responses. This may be particularly important for people with insulin resistance, prediabetes, or diabetes management goals.
However, in situations where blood glucose levels need to rise quickly, such as during hypoglycaemia (a hypo) or during sport, rapidly available carbohydrates are generally preferred as they may help provide faster glucose availability.
The glycaemic index (GI) of a meal can be influenced by a range of factors, including the type of carbohydrate eaten, as well as the amount of protein, fat and fibre consumed alongside it, which may slow digestion and carbohydrate absorption.
How is GI Measured?
GI testing is conducted in healthy volunteers using internationally standardised testing methods. Participants consume a measured amount of carbohydrate from a test food, and blood glucose levels are measured over a set period of time. The response is then compared to a reference carbohydrate such as glucose to determine the GI value of the food.
The Sydney University Glycemic Index Research Service (SUGiRS) is one of the world’s leading GI testing organisations and manages the international GI database.
GI Search Database: https://glycemicindex.com/gi-search/
More information about GI testing and research: https://glycemicindex.com/glycemic-index-testing-research/