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The nuts and bolts of carb counting

If you’re living with Type 1 diabetes, you might find that carbohydrate counting, or carb counting, is an effective way of managing your blood glucose levels – it means that your insulin dose can be individually matched to the amount of carbohydrate you eat and drink.

Being aware of the amount of carbs in food and drinks is important for everyone with diabetes, but carb counting is particularly helpful for those on basal-bolus insulin regimen. This is when the person with diabetes (mostly Type 1 diabetes) injects insulin with each meal or uses an insulin pump.

Although carb counting requires a great deal of time and effort, once mastered it can lead to better blood glucose control and greater flexibility in the times and amount of carbohydrate you eat. It doesn't mean total freedom to eat whatever you want in excess as this would be unhealthy for anyone, although special occasions and treats can be more easily incorporated and insulin adjusted to match.

Carbohydrates can be counted in two ways, in grams or as carbohydrate portions (CP). One CP is usually equal to 10g of carbohydrate. It is important that you find the method that works best for you.

Once you’ve got to grips with estimating the amount of carbohydrate you are going to eat and drink, the next key piece of information you need is your insulin-to-carbohydrate ratio. Insulin-to-carbohydrate ratios vary from person to person, so you will have your own personal ratio depending on your age, weight, activity levels and how sensitive you are to insulin. Your diabetes healthcare team will help you work it out and, eventually, you may even have a different insulin to carbohydrate ratio for each meal. They will usually estimate your starting insulin-to-carb ratio and subsequently fine-tune this based on your blood glucose control.

If you know how many grams of carbohydrate are in a meal and your insulin-to-carb ratio then you can work out the number of units of bolus insulin you need to take for the meal.

For example: if you are planning to eat 70g of carbohydrate at your meal and your insulin to carbohydrate ratio is 1 unit of bolus insulin for every 10g carbohydrate then you will need to take 7 units of bolus insulin.

The amount you actually take will also depend on other factors such as your blood glucose level, illness or planned activity.

How can I count the amount carbohydrate I am eating and drinking?

There are five ways you can count carbohydrate in food and drink.

1. Food labels – using the carbohydrate per portion value

If you look at the labelling on the back of a ready-meal, you'll see something that looks like this:

Typical Values 100g contains Each oven baked meal (317g) contains
Energy 433kJ (103kcal) 1372kJ (325kcal)
Fat 1.7g 5.4g
Saturates 0.9g 2.9g
Carbohydrate 14.1g 44.7g
Of which sugars 2.0g 6.3g
Fibre 1.2g 3.8g
Protein 7.1g 22.5g
Salt 0.4g 1.3g

If you ate all of this ready meal, the amount of carbohydrate you would count is 44.7g of carbohydrate. It is important to count the total amount of carbohydrate and not the 'of which sugars' value. When using the per portion value be sure that this is the actual portion you are planning to eat.

2. Food labels – using the carbohydrate per 100g value

On the back of foods like pasta or, in this case, basmati rice, you'll see food labelling information like this:

Typical Values As sold 100g contains
Energy 1515kJ (360kcal)
Fat 1.0g
Saturates 0.2g
Carbohydrate 77.4g
Of which sugars 0.2g
Fibre 1.8g
Protein 8.5g
Salt <0.01g

When using the per 100g value, calculate the carbohydrate for the actual amount of the food or drink that you are going to have. For example, if you were planning to cook and eat 80g of this rice the amount of carbohydrate you would count is 61.9g of carbohydrate and not 77.4g. It is worthwhile investing in a good set of scales that are flat based, digital and can be zeroed. It is also important that your scales are accurate to within 5g. The cooked weight of foods like pasta, rice and potatoes will vary from the raw or pre-cooked weight, so check which values you are using.

3. Reference lists and visual guides

What should you do when food doesn't carry a nutrition information label, or you're eating out and don't have the recipe for what you are eating – or a set of scales? Although these times can be more challenging, reference lists and visual guides, such as Carbs & Cals, will come to your rescue and help you estimate carbohydrate. They list the amount of carbohydrate in handy measures, such as “1 bread roll “, “1 medium banana”, or “1 scoop of ice cream”. And some contain pictures for comparing, too.

4. Recipe nutrition information

Using the Diabetes UK recipe pages or cookbooks can take the hard work out of calculating the carbohydrate content of more that 250 recipes for you.

And there's no need to throw out your favourite recipes and cookbooks. Taking the time to work out the carbohydrate values of your day-to-day meals helps you build up a personal reference list that you can use again and again.

5. Restaurant and cafe nutrition information

Many restaurants and cafes will now list nutritional information for their products online. You may find information that looks like this:

Bacon breakfast roll

  Per 100 g Per 114 g serving
Energy 1381.6 kJ 575 kJ
Energy 328.1 kcal 374 kcal
Fat 19.2 g 21.9 g
of which saturates
6.8 g

7.8 g
Carbohydrate 22.2 g 25.3 g
of which sugars
1.4 g

1.6 g
Fibre 1.3 g 1.5 g
Protein 15.8 g 18 g
Salt 3.07 g 3.5 g

Many restaurants and snack bars are now providing nutrition information for their menus in a response to us all becoming more health aware. The nutrition information for this bacon breakfast roll was found in seconds after a quick search on the internet. Bear in mind that the values are average values and the dish that you are served may vary in size and content. You still need to use your judgement and experience

Three ways to start carbohydrate counting today

Ever heard the phrase “don't run before you can walk”? Well, it's certainly true with carbohydrate counting. Your first step has to be finding out more (see below). But there's no harm in the meantime putting down the foundations for building a new way to manage your diabetes.

  1. Do you know which of your food and drink contain carbohydrate? Stop, think and make a mental note of which food and drink will need to be counted.
  2. Get label savvy – scrutinise the nutrition labels. Pull the food and drink out of your kitchen cupboards and find out just how much information you have to hand.
  3. Make carbohydrate your Mastermind specialist subject. Practise estimating the carbohydrate content of your meals – use reference lists to check your accuracy.

Interested and want to know more?

To carbohydrate count successfully you will need a whole lot more information than this article. You will need to learn all about carbohydrates, learn how to adjust your insulin and be dedicated to monitoring your blood glucose levels frequently. You will also need the support of professionals either in the form of your diabetes healthcare team or one of the structured diabetes education courses available. You can find out about courses available in your area from your diabetes healthcare team.

Carb counting courses

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