On this page

What is the Glycaemic index (GI)?

Mixture of fruits on a wooden chopping board
On this page

According to Diabetes UK, being aware of the amount of carbohydrate in food and drinks is important for everyone with diabetes.

This isn’t the same as cutting out carbs altogether – we all need some carbs every day, as they’re our main source of energy. But if you’re watching your carbs to try to maintain healthy blood glucose levels, you may want to consider using the glycaemic index (GI).

What does GI measure?

GI measures the effect foods containing carbs have on blood glucose levels, ranking them from 0 – 100.

  • Foods that rank 70 or higher are considered high GI
  • Those between 55 – 70 classed as medium GP
  • 0 – 55 are low GI foods

If a food has a high GI, it means its carbs are absorbed quickly, which can raise blood glucose levels sharply. Foods with a medium GI have a moderate effect on your blood glucose, while low GI foods are absorbed slowly (these are also called slow-release carbs).

Low GI foods

Most fruits and non-starchy vegetables plus carrots, sweet potato and yams have a GI of 55 or less, as do beans and lentils.

Examples of low GI grains include:

  • Oatmeal
  • Oat bran
  • Barley
  • Bulgur wheat

Breads with a low GI include pumpernickel and multigrain/granary bread.

Medium GI foods

Brown, wild and basmati rice are medium GI. Some breads are too, including whole wheat, rye and pita. And while regular oatmeal and oat bran have a low GI, quick-cook oats are medium GI.

High GI foods

Foods that include highly refined carbs have a high GI, these include:

  • White bread and rolls
  • Bagels
  • Pretzels
  • Wheat crackers
  • White rice
  • Rice cakes

Potatoes have a high GI too. Some breakfast cereals such as corn flakes, puffed rice and instant oats are high GI, while fruits that are ranked high on the GI scale include melons and pineapple.

Can GI help me control blood sugar levels?

Following a low GI diet may help you to lose weight and control your blood sugar levels. But it doesn’t mean you should eat nothing but low GI foods. Most experts simply suggest using GI as a tool to help you keep your meals balanced.

For instance, if you’re eating something with a high GI, combining it with low or medium GI foods can help balance out the effect the meal as a whole has on your blood sugar levels.

Our top tips for GI foods

  • Try to include one low GI food with each meal.
  • Choose low GI cereals – if you like porridge, make it from regular oats or oat bran, rather than quick or instant oats.
  • Swap white or brown bread and rolls for bread made with grains and seeds.
  • Pick sweet potato and yams instead of white potatoes (or if you’re having white potatoes, makes sure they still have their skins on).
  • Try having quinoa or bulgur wheat instead of white rice, and cook your pasta until it’s al dente instead of soft (al dente pasta has a lower GI than pasta that’s been cooked for longer).
  • If you don’t do so already, make beans and lentils part of your diet on a regular basis.

Read our diabetes food guide for more inspiration and why not try our no bake cinnamon oatmeal energy balls recipe.