Carb Counting Maths

I never thought I would be using maths again in my life, who needs calculus and trig for day to day work. Carbohydrate counting feels like I’m back in maths class, it’s like learning a foreign language. It is so confusing!

With type 1 diabetes you inject your insulin in regards to how many carbohydrates you have eaten in your food. Everyone’s ratio is different based on to sensitive their bodies are to carbs or not, but my ratio is 1:15. This means I inject 1 unit of novorapid to every 15g of carbohydrates that I eat in that meal or snack. Bit lost already? Don’t worry so was I when I had my first lesson in the hospital after being diagnosed.

Carbohydrate counting is super easy if you are eating packaged foods. All the information you need is on the back of a packet. On the back of the packet you can either go by 100g of the particular food or per serving under carbohydrates. This is so easy for when eating a snack from a packet, like a muesli bar. The per serving is for 1 bar, and it says 30g of carbs which equals 2 units of insulin to inject before eating the muesli bar.

Simple right? What happens then when your having say muesli with yoghurt. Uh oh, time to remember 5th form maths. Lets check out mum’s muesli that she eats in the morning. 100g of carbohydrates is 49.6g of carbohydrates. Then we have mums greek yoghurt which per 100g has 4.6g of carbs.


But who eats 100g of muesli and 100g of yoghurt. Instead of just pouring the muesli out of the box into my bowl in the morning, I have to put the amount I want for breakfast into a bowl to measure it, and then same for the yoghurt as well for an exact amount of carbohydrates to inject for.

For this example (and not to complicate my maths and your brains lol), lets say 100g of muesli and 25g of yoghurt which would equal 49.6g of carbs for muesli and 0.184g of carbs for yoghurt. Add these together and we get 49.784g of carbohydrates for breakfast so that results in 3.3 units of insulin.

And we know hit another problem, my novorapid insulin pen only allows be to inject at .5units. For breakfast I could either inject 3 units of insulin and risk having my bloods run a bit higher after breakfast or inject 3.5 units of insulin and risk having a low blood sugar after breakfast. Generally its a wee bit easier to run a bit higher and inject some more insulin later on in the day then run low and the complications that comes with that.

Seems not too bad huh. But what happens when your cooking dinner and food isn’t from a packet or you are out at a restaurant or cafe having a meal. Guessing insulin can become a problem with the unexpected lows or highs after your meal, but again generally its better to inject a little bit less and have a high after a meal then it is to inject more and have a low during dinner or when you get home, stopping you from going ahead with plans after your meal.

Nutritional counting apps are an amazing tool for homemade meals but it is very time consuming. Homemade meals means figuring out the carb count of each item of food and then adding it all together to get a total amount for the meal, and then deciding how much of that meal you are planning on eating and injecting the correct amount of insulin on that much food.

Getting a general idea of carbohydrate counts on food makes it easier to guess how many carbs are in your meal without needing to go through the process and counting each individual food. And just like everyone else, you end up eating the same thing for breakfast, lunch and dinner making it easier to no what to inject for these meals.

Counting carbohydrates is such a mission and it need to be done for everything to be eaten even if it’s just a quick snack. Numbers are constantly going on in my F98A92DC-BAC8-47B9-BE50-B11CBAEE3B9Ebrain and I look at food for the number of carbs it involves not the food its self. I get
it wrong a lot of the time, injecting too much insulin or not enough. But overall I can be pretty good at it, and eating a low carb diet full of whole foods, fruits and vegetables allows me to be pretty good at judging.

How do you count carbs? Manually or with a app?




11 thoughts on “Carb Counting Maths”

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