Carbohydrate can be counted in grams, carbohydrate portions or exchanges. In the UK each portion or exchange is usually 10g of carbohydrate and in the US and Australia it is 15g (so if you read diabetes information on the internet from these countries, remember that it’s different from the UK).
Nutrition information labels on packaged food can tell you how much carbohydrate (in grams) is in 100g or in a portion of that food. Use the ‘total carbohydrate’ figure, not the ‘of which sugars’ value when matching insulin.
Your paediatric diabetes team may provide you with a list of carbohydrate foods and the amount of carbohydrate they contain. There are also books often aimed at people trying to lose weight (called calorie counters), but they list the grams of carbohydrate, either per 100g of food or per portion of food.There are also books with photos of different portions of food and their carbohydrate values, and even an ‘app’ for smartphones to help.
The amount of insulin your child will need will be determined by your paediatric diabetes team, and will depend on their age, weight, activity levels and how long they have had diabetes. If you know how many grams (or portions) of carbohydrate are in a meal, and how much insulin they need per 10g of carbohydrate (or per portion), then you can work out the number of units for the meal.
Wherever possible, injections of rapid-acting insulin or pump doses should be given before eating. If your child’s appetite is unpredictable then you could give the injection immediately after the meal. On mixed insulin, the injection should always be given before the meal. On a pump, some insulin should always be given before eating, and then topped up after the meal if necessary.
Digital scales are very useful to weigh portion sizes. Breakfast cereals, rice, pasta and potato are very difficult to guess the carbohydrate content as the portion sizes vary so much between different people. Using scales you can work this out accurately, and then know what your child’s own portion size contains. Even if you don’t weigh food every time, it is worth revisiting every six months or so as their portion size may change as they get bigger.