Glycemic index (GI) is a measure of how quickly a food can make your blood sugar (glucose) rise. Only foods that contain carbohydrates have a GI. Foods such as oils, fats, and meats do not have a GI.
In general, low GI foods increase glucose slowly in your body. Foods with a high GI increase blood glucose quickly. If you have diabetes, high GI foods can make it harder to control diabetes.
Not all carbohydrates work the same in the body. Some trigger a quick spike in blood sugar, while others work more slowly, keeping blood sugar more even. The glycemic index addresses these differences by assigning a number to foods that reflects how quickly they increase blood glucose compared to pure glucose (sugar).
The GI scale goes from 0 to 100. Pure glucose has the highest GI and is given a value of 100.
Slowly absorbed carbohydrates have a low GI rating (55 or below), and include most fruits and vegetables, unsweetened milk, nuts, pulses, some wholegrain cereals and bread
Research has shown that choosing low-GI foods can particularly help manage long-term blood glucose (HbA1c) levels in people with Type 2 diabetes. There is less evidence to support this in people with Type 1 diabetes, but we know that on a day-to-day basis choosing low GI foods can help keep blood glucose levels steady after eating.
Not all low-GI foods are healthy choices – most chocolates, for example, have a low-GI because of their fat content, which slows down the absorption of carbohydrate.
Eating to manage your diabetes isn’t just about GI ratings. Think of the bigger picture and choose foods high in fiber and wholegrains, as well as low in saturated fat, salt and sugar, as part of a long-term healthy diet.
Eating low GI foods can help you gain tighter control over your blood sugar. Paying attention to the GI of foods can be another tool to help manage diabetes, along with carbohydrate counting. Following a low-GI diet also may help with weight loss.