A low glycemic index diet may be followed by people with diabetes as, when used alongside portion control, it can be effective in reducing rapid rises in blood glucose levels.

An extension of the glycemic index is glycemic load which takes into account both the GI of a food and the total carbohydrate content.

What is the glycemic index?

The glycemic index (GI) is a ranking system used to work out how quickly food is broken down in the body to form glucose. GI is the basis of how the glycemic load of food is assessed.

Low GI foods, such as whole grain bread, milk and beans are converted into energy more slowly, while high GI foods, such as white bread and biscuits, are broken down more quickly.

GI foods and diabetes

Low GI foods can be beneficial for people with diabetes, as the delayed release of energy prevents quick rises in blood sugar levels.

You are also likely to feel more satiated over a long period of time by eating low GI foods, and feel less hungry in-between meals.

In comparison, high GI foods often contain fast-acting carbohydrates or sugars. As a result, people who produce their own insulin require an insulin surge to counteract this quick rise in blood glucose levels. For people with diabetes unable to produce insulin, a larger dose is required for high GI foods.  This can lead to feelings of hunger within a few hours.

People with diabetes need to take care eating high GI foods, as the body’s ability to control blood glucose levels can be greatly reduced.

Low GI diets


The benefits of following a low GI diet include:

  • Greater nutritional value than high GI foods
  • Less demand for immediate insulin after eating
  • Longer releases of energy
  • A varied diet can be eaten


The main disadvantage of a low GI is that carbohydrate content can still be high in some foods, despite being low GI. One example of this is a large portion of bran-based cereal, which could still lead to high blood glucose levels over a period of hours.

This can be addressed, though, by managing portion sizes. Keeping portions of carbohydrate down can reduce caloric intake and the need for insulin, as well as enable weight loss. Keeping at a healthy weight is a key factor in maintaining good diabetes control.

What foods are considered low GI?

Some of the low GI foods that are considered to be suitable for people with diabetes include:

  • Lean meats
  • Non-starchy vegetables
  • Whole grains
  • Nuts
  • Legumes
  • Fruit

GI fruit and vegetables

You should take particular care with fruit and vegetables on a low GI diet, as the values of these food groups can significantly vary.

  • Lower GI fruits – include berries, plums, kiwi fruit and grapefruit
  • Higher GI fruits – include bananas, oranges, mango, grapes, raisins, dates and pears
  • Lower GI vegetables – include lettuce, broccoli, cabbage, cauliflower and peppers
  • Higher GI vegetables – include potatoes, parsnips, beetroots and sweetcorn