With all the hype about low carbohydrate diets over the past few years, you could easily be mistaken to think that carbs are the enemy and something to be avoided at all cost. But if you have type 1 diabetes, carbs are really important - actually the most important part of your diet. You don't actually need to eat more or less carbs than normal if you have diabetes, but you do need to balance your intake of carbs with the amount of insulin you take and the exercise you do. Let me explain...

Food is made up of protein, fat and carbohydrate along with vitamins, minerals, dietary fibre and water. All of these are an important part of a healthy diet but it is the carbs that impact most on blood glucose levels.

When you eat carbs, they break down to glucose which is absorbed into your bloodstream. You then need insulin to get the glucose from the bloodstream into your muscles and cells to use for energy. In someone without diabetes, the body always produces just the right amount of insulin to deal with the carbs that they eat. But when you have type 1 diabetes, this doesn't happen. Most type 1s inject a similar amount of insulin each day, which means that you really need to be eating a similar amount of carbs each day to avoid your blood glucose levels going up too high or down too low.

There are other factors, such as exercise and stress, that make this relationship a bit more confusing, but essentially insulin and carbs need to be matched.

You will need to learn how much carbohydrate is in the food you eat. A common tool used is carbohydrate portions or exchanges, which is the amount of a food providing 15g of carbohydrate.

Examples of a portion/exchange (or 15g) of carbohydrate:

• a slice of bread
• an apple
• 2 Weet-Bix
• a glass of milk.

This means that you could have either 2 slices of bread and an apple OR 4 Weet-Bix with a cup of milk and in both cases you would be having about the same amount (3 portions) of carbs. And for both meals you would need about the same amount of insulin.

A dietitian can help you to work out the amounts of carbs you need to eat from day to day and meal to meal and will work with you and your endo to determine the right amount of insulin to take depending on the amount of carbs you eat.

So which foods contain carbs?
Carbs are made up of starches and sugars. Starches include breads, cereals, pasta, rice, starchy vegetables such as potato, sweet potato and corn, and legumes. Sugars include added sugar as well as the natural sugars in fruit and dairy products such as milk, yoghurt and ice-cream.

Are all carbs the same?
In the past people with diabetes were told not to eat sugary foods and to consume only carbs from starchy foods. But we now know that foods are more complex than we previously thought. Some sugary foods, particularly the natural sugars in fruit and dairy products, increase blood glucose levels only slowly, while some starchy foods, such as white bread, cornflakes and potato will raise blood glucose levels more quickly. The measure of how quickly or slowly a food raises blood glucose levels is called glycemic index (GI) and is explained in more detail on the next page.

The Glycemic Index (GI Factor) tells us that:

• The amount of sugar in a food isn't a good indicator of how likely the food is to raise blood glucose levels
• People with type 1 diabetes don't need to avoid sugar altogether - the most important thing is eating a similar amount of carbs from day to day, regardless of where the carbs come from
• Even if you eat the same amount of carbs from day to day you may get a different blood glucose response if the GI of the carbs you eat is different.

In general it is good to eat more low GI carbs, except during episodes of hypoglycemia when high GI carbs will bring the blood glucose level back to normal much faster.

A dietitian will help you to work out an eating plan to suit your needs, food preferences and lifestyle. They will also be able to explain more about carbs and GI and to help you to work out how different foods affect your blood glucose levels.

To find a dietitian who specialises in diabetes, contact your local diabetes center, Diabetes Australia in your state, or DAA (Dietitians Association of Australia). Your endocrinologist and Diabetes Educator should also be able to help you.

For more information on eating with diabetes, and the carbohydrate content of foods, you may wish to buy a copy of 'The New Traffic Light Guide to Diabetes', or check out one of the many online carb counters such as www.calorieking.com.au. 

Many thanks to Kate Marsh, Dietitian and Diabetes Educator in Sydney for preparing this information for the Starter Kit.