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Why learn to count carbohydrate?
This leaflet is aimed at people who are interested in starting to develop skills in carbohydrate counting. This may be as a precursor to attending a DAFNE course. It is helpful to be under the care of the diabetes multidisciplinary team whilst learning to do this, so they can support you with it.
Learning to carbohydrate count does take some dedication. Once you have developed the skills, you will be able to adjust your doses of insulin according to what you eat and achieve better blood glucose control.
You need to be on a basal bolus (or ’qds’) insulin regimen. This includes a basal (long acting) insulin, such as Lantus or Levemir, along with quick acting insulin given with meals, such as Humalog, NovoRapid, Fiasp or Lyumjev.
Carbohydrate is the main nutrient that raises blood glucose levels. The amount of carbohydrate you eat determines the amount of insulin you need.
Identifying the foods and drinks that contain carbohydrate that need to be counted
Sources of Carbohydrate
Starchy
- Bread including naan, chapatti and roti
- Grains e.g. pasta, rice, bulgar wheat, quinoa, couscous
- Potatoes including sweet and white potato
- Breakfast cereals and oats
- Savoury crackers
- Foods made from flours including wheat, rice, chickpea
Natural sugars
- Milk
- Yoghurt
- Fruit
- Fruit juice
- Dried fruit
Added sugars
- Cakes
- Biscuits
- Sweets
- Chocolate
- Sugary drinks
Do not forget carbohydrate is still found in small quantities in processed foods such as:
- Sauces and gravies containing thickening agents or added sugar
- Battered or crumbed foods
- Vegetarian foods e.g. vegetarian sausages
- Some salad dressings
Some foods contain smaller amounts of carbohydrate but are very slow release and cause a minimal rise in blood glucose levels therefore do not need to be counted. These include:
- Pulse vegetables e.g. lentils, chickpeas, butter beans, kidney beans, peas
- Cherries and grapefruit
- Barley
- Nuts
- Vegetables e.g. salad vegetables, root vegetables, broccoli, cauliflower, cabbage
If you eat these foods in large quantities, you may notice a rise in your blood glucose levels and so could consider giving a proportion of the insulin you would normally give for the amount of carbohydrate.
Baked beans contain carbohydrate from the beans and from the sauce. Only the carbohydrate from the sauce will cause your blood glucose levels to rise. When working out the carbohydrate content of baked beans, only count half the total amount of the carbohydrate listed on the label, in your reference guide or app.
So which foods do not need to be counted?
Foods that do not contain carbohydrate and therefore do not need to be counted include:
- Meats, fish, poultry (unless coated in breadcrumbs)*
- Eggs
- Cheese
- Fats such as spreading fat, butter, mayonnaise
- Oils
* Sausages often contain cereal fillers but due to the higher fat content this carbohydrate usually doesn’t result in a glucose rise, therefore we would not include it in our carb counting to start off with.
Calculating the carbohydrate content of your food
You will count carbohydrate in grams initially. Sometimes you will see people count in carbohydrate portions or CPs. It is helpful to be as accurate as possible as each 10g makes a difference of 2-3mmol/l to your glucose levels.
Firstly, you will need to calculate the carbohydrate content of the foods in your meal. The most accurate way to count carbohydrate is to weigh your food with kitchen digital scales. You can use the resources below to help you:
- Food labels (from the foods you are eating)
- Carbs and Cals book, or app (available from the App Store or Google Play, subscription charge applies but 14 day free trial available to try before you buy) Carbs & Cals | Dieting & Calorie Counting Books & App (carbsandcals.com)
- My Fitness Pal app (free) or Nutrachek app (subscription charge)
- Carbohydrate Portion List
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Activity: please watch these videos to help with working out the Carbohydrate counting using the Carbs & Cals 'Carb & Calorie Counter' Book - YouTube Carbohydrate counting using a Carbohydrate Portion List - Youtube |
Food Labels
When counting carbohydrate, you need to look at the total carbohydrate on the food label. The carbohydrate content for a given food may be listed “per 100g, “/100g”, “per suggested serving size” or “per item”. Be careful to check that your serving size is the same weight (if you use the suggested size).
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Activity: please watch this video to help with working out the |
Once you have weighed your food and looked up the carbohydrate content, use the following formula to work out the carbohydrate content of your serving*.
Example
- Carbohydrate content of new potatoes (boiled) = 15g/100g
- Weight of new boiled potato (your serving) = 120g
- Carbohydrate content of your serving =
- 15/100 x 120 = 18g carbohydrate
- You could round the 18g to 20g to make the numbers easier *The Carbs and Cals app can do this calculation for you.
Tips to help with carbohydrate counting
- If your meal includes different sources of carbohydrate, add up the carbs from them all and then round to the nearest 5g or 10g
- Be careful not to confuse the weight of the food with the carbohydrate content, as this could result in you giving yourself too much insulin
- Serve rice and pasta separately to the sauce while you are getting used to visualising your serving sizes—this will help when you are unable to weigh your food
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Activity: please watch this video to learn how handy measures speed up carbohydrate counting |
- Make a note of the carbohydrate content of foods that you eat regularly on the table on page 10. You can start to make use of handy measures here too.
Carbohydrate content of your favourite foods
To save time, record the carbohydrate content of foods or drinks you commonly consume in the space below and start to work out any handy measures that you can use, after watching the video:
Post meal glucose rises
It is recommended to inject your quick acting insulin 10-15 minutes before eating to minimise the post meal glucose rise. If you are using ultra quick acting insulins, like Lyumjev and Fiasp, you are unlikely to need to inject so long before eating. The other time where this may not be needed is when eating high fat/high protein meals.
Snacks
- Snacks containing more than 10g carbohydrate should be covered by some insulin. Use the insulin to carb ratio (if you are using one) for the nearest meal, or 1 unit per 10g carbohydrate, if you are unsure
- Your glucose may be above target if you have had a snack near to a meal and taken insulin. Consider any remaining active insulin before correcting at the next mealtime
- If you are planning to be more active, you may decide the quick acting insulin is not required for the snack.
Other factors affecting glucose levels
Physical activity and alcohol have an effect on glucose levels, and it is helpful to record these on your carbohydrate counting diary when filling this in.
Insulin dose adjustment
Background insulin
Sometimes we ask people to carry out some checks on their background insulin dose, this will be discussed in more detail during your appointments.
Insulin to carbohydrate ratio
When adjusting insulin according to your meals, you will use an insulin to carbohydrate ratio. This means that each unit of insulin will cover a certain number of grams of carbohydrate.
Some people require different insulin to carbohydrate ratios at different mealtimes. This can be identified by looking at patterns in your blood glucose checks.
Test your insulin to carbohydrate ratio by planning some easy to carb count meals to check the insulin dose given is bringing you back to within your target range prior to the next meal. This will only work if your background insulin dose is correct.
Monitoring your glucose levels
It is recommended that you check your blood glucose before meals and before bed and any other time you feel it is required. When you check your glucose level, we suggest you aim for:
- 5.0-7.0 mmol/l before breakfast
- 4.0-7.0 mmol/l before other meals
- 5.0-9.0 mmol/l before bed
If your glucose levels have been running much higher than the above ranges, these targets might be too low. In this case it is recommended you aim for the top end of the target range. Your diabetes team will be able to advise on suitable targets for you if you are not sure.
Correction of high blood glucose using your correction dose
Your correction dose is the number of mmol/L, 1 unit of insulin will reduce your glucose levels by. For most people 1 extra unit of quick acting insulin decreases blood glucose by 2.0-3.0 mmol/L.
Example
The correction dose is as follows:
1 unit of insulin reduces blood glucose by 3mmol/L.
If the pre-meal blood glucose was 13mmol/L and the pre-meal target is 7mmol/L, you would need to bring the blood glucose down by 6 mmol/L.
- 13 - 7 = 6mmol/l
- 6 ÷ 3 = 2 units
Therefore, you would need to add this 2-unit correction to your mealtime insulin dose.
Test your correction dose (or insulin sensitivity) by correcting an elevated glucose result when not eating any food and checking to see if it brings you back to your target 4 hours later. This will only work if your background insulin dose is correct.
Remember the acting time of your rapid insulin is around 4 hours. It is tempting to add in additional corrective doses before the initial dose is out of your system. This can lead to insulin stacking and potentially results in hypoglycaemia therefore it is not recommended to correct between meals. Try and stick to adding corrective doses before a meal only
Hypo treatment
If your glucose level falls below 4.0 mmol/L*, then treat the hypo as follows:
Step 1
- Take 15-20g rapid acting carbohydrate
- 3-4 large jelly babies
- 6-7 Dextrose tablets or 4-5 glucose tablets
- 170- 200mls Lucozade original
- 160 - 200mls fruit juice
- 150mls cola (mini can)
Step 2
- Wait 15 minutes
- Re-check your blood glucose level. If still less than 4.0 mmol/L then repeat step 1 until your blood glucose level is greater than 4.0 mmol/L*
Step 3
| If the hypo occurs | Action to take |
| Within the 1 hour of next meal | Eat your next meal as planned |
| 1-2 hours until next meal | Consider an additional 10g slower-acting carbohydrate |
| More than 2 hours until the next meal | Consider an additional 20g slower action carbohydrate |
* If a low glucose level is identified using a form of continuous glucose monitoring, it is important to do a finger prick check to confirm the low glucose level is correct. In addition, it is helpful to use finger prick checks to review whether the hypo treatment has been effective, as the continuous glucose monitoring devices measure interstitial fluid which can be more than five minutes behind actual glucose levels.
Contact us
If you have any queries relating to this information, please contact the Dietetics service.
About this information
Service:
Dietetics
Reference:
DT/020
Approval date:
30 April 2024
Review date:
29 April 2027
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.