Living with Diabetes

Carbohydrates – good or bad?

What are carbohydrates?

Carbohydrates are an essential part of diet which consist of sugars, starches and fibre. Carbohydrates are broken down to glucose which is an essential fuel for the body.

Why do we need carbohydrates?

Carbohydrates provide an important source of energy. If the diet is low in carbohydrate you use other foods such as dietary protein to produce glucose.

What are the main carbohydrates in the diet?

  • Starchy foods have a high carbohydrate content – potatoes, pulses, rice, bread
  • Fruits and vegetables,
  • jams and confectionary (cakes and sweets),
  • soft drinks
  • milk

In most diets starches account for about 60% of carbohydrate and sugars make up about 40%.

What is the difference between Complex carbohydrates and sugars?

Complex carbohydrates or polysaccharides are made up of long chains of simple sugars. They include dietary fibre and starches. A molecule of starch may contain as many as a thousand units of sugar.

These foods increase blood sugar don’t they?

Yes. Different types of carbohydrates produce varying responses in insulin and blood sugar. However when it comes to glucose control it seems that all carbohydrates are more or less the same. However research has shown that the total amount of carbohydrate you eat will affect your blood sugar levels. Evenly distributing your carbohydrate intake through the day will help control your blood sugar.

Aren’t high blood sugar levels after meals bad for you?

There is some evidence that high blood sugar levels after meals may be linked to an increased risk of cardiovascular disease.

How much carbohydrate can I eat?

Discuss this with your dietician. The amount of carbohydrate you should eat depends on your lifestyle and the amount of exercise you take. The DAFNE study has shown that people with type 1 diabetes can have unrestricted intake of carbohydrate and still achieve good control. This approach requires knowledge and skills to maintain good control by adjusting dose of insulin. The DAFNE study is described in detail on another page.

Other studies on individuals with type 2 diabetes have demonstrated worse control and insulin resistance when carbohydrates account for over 60% of total energy intake.

Does the type of carbohydrate I eat matter?

No. There is no evidence that any type of carbohydrate is linked to poor blood sugar control. Provided the amounts of carbohydrates consumed are similar, there is no evidence that varying the proportion of starches or sugars makes a difference to your control.

What are the sources of sugar?

Fruits and vegetables. Lactose in milk. Table sugar, fruit juice, honey, jam and confectionary.

What is fibre?

Fibre consists of complex carbohydrates which we cannot digest in the small bowel. These carbohydrates travel through to the large bowel where bacteria cause them to ferment. Carbohydrates found in fibre include pectin, guar gum and cellulose.

What purpose does fibre serve?

Fibre helps you to ‘fill up’ without providing too many calories. It adds bulk to the stool and helps promote regular bowel movements. Fibre also helps you to lose weight and delays absorption of sugars into the bloodstream helping to control blood sugar increases.

What carbohydrates should I include in my diet?

  • Bread and cereal made from ‘whole grain’
  • Rice
  • Lentils and legumes
  • Skimmed milk
  • Fresh fruit
  • Fruit juices without added sugar

Are low carbohydrate diets good for people with diabetes?

There has been a lot of recent interest in low carbohydrate diets. This subject is discussed in a separate leaflet. There have been reports of weight loss with these diets but the long term safety and efficacy has not been proven.


Dr Nishan Wijenaike, Consultant Physician
West Suffolk Diabetes Service
September 2003