Carbohydrates and diabetes:
What you need to know

Carbohydrates are our main source of energy and provide important nutrients for good health and a healthy, balanced diet. All the carbohydrates you eat and drink are broken down into glucose. The type, and amount, you consume can make a difference to your blood glucose levels and diabetes management.

The two main types of carbohydrates

photograph of starchy foods

  • Starchy foods: these include bread, pasta, potatoes, yams, breakfast cereals and couscous.
  • Sugars: these can be divided into naturally occurring and added sugars:
    • Naturally occurring: sugars found in fruits (fructose) and some dairy foods (lactose).
    • Added sugars: found in sweets, chocolate, sugary drinks and desserts.


This is another type of carbohydrate, which you can’t digest.

  • Insoluble fibre, such as is found in wholemeal bread, brown rice and wholegrain cereals, helps keep the digestive system healthy.
  • Soluble fibre, such as bananas, apples, carrots, potatoes, oats and barley, helps to keep your blood glucose and cholesterol under control.

Make sure you eat both types of fibre regularly. Good sources of fibre include fruit and veg, nuts and seeds, oats, wholegrain breads and pulses.

How much?

Everyone needs some carbohydrate every day. The actual amount that you need to eat will depend on your age, activity levels and the goals you – and your family – are trying to achieve, for example trying to lose weight, improve blood glucose levels or improve sports performance. The total amount of carbohydrate eaten will have the biggest effect on your glucose levels.

Insulin and carb counting

If you’re living with diabetes, and take insulin, you’ll need to take that into account when eating carbs. Learn about which foods contain carbohydrates, how to estimate carbohydrate portions and how to monitor their effect on blood glucose levels.

There are special courses available, such as the DAFNE course, which your diabetes healthcare team can tell you about.

Our downloadable PDF e-book, Carbs Count, provides an introduction to carbohydrate counting and insulin dose adjustment. It takes you through the essential information, with practical examples and exercises. You can download it for free through our online shop.

illustration of a loaf of bread and a potato

Three ways to include good carbohydrates in your diet

  • Choose wholegrain breads and cereals.
  • Have fruit whole, rather than as a juice. Eating an apple with the skin on, for example, will provide more fibre than drinking a glass of apple juice.
  • Ring the changes with quinoa and couscous as an alternative to pasta.

How does carbohydrate affect anyone with Type 1 diabetes?

All carbohydrate is converted into glucose. In someone without diabetes, the body produces insulin automatically to deal with the glucose that enters the blood from the carbohydrate-containing food that we eat and drink.

In Type 1 diabetes the same principle applies but because your body doesn’t produce any insulin, you have to take insulin, either by injections or a pump. This will help to lower the glucose in the blood after eating carbohydrate-containing foods. Most people follow twice-daily or basal bolus insulin regimes.

  • Twice-daily insulin

    If you are taking fixed amounts of insulin twice a day you may find it beneficial to have consistent amounts of carbohydrates on a day-to-day basis, and eat roughly the same amount of carbohydrate at similar times each day. More carbohydrate than usual can cause blood glucose levels to go too high, and less than usual can cause a hypo (low blood glucose levels).

  • Basal bolus insulin

    If you are using a basal bolus insulin regime or pump you can be much more flexible in how much insulin you take and when you take it. Most people following this regimen will count carbohydrates that they eat and drink and then calculate how much insulin they need to take. The amount of insulin will change depending on how much carbohydrate they have eaten.

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