How do you caluculate...

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Gill28 1 post


I'm a final year Design student, trying to design a device which make it alot easier for diabetics to manage their food.
I'm trying to understand how DAFNE actually works.
I'd be very grateful if someone could please take the time just to quickly explain what DAFNE involves and what calculations you have to make in order to work out how much insulin you need to take?



NiVZ DAFNE Graduate
NHS Grampian
82 posts

Hi Gill,

DAFNE covers a wide range of topics, including illness, alcohol, as well as food.

For the food part of things it's just a case of applying a ratio of insulin to carbohydrate. In DAFNE 1CP (Carbohydrate Portion) is 10g of carbs. Therefore a 1:1 ration means 1 unit of insulin to 10g of carbs. Some people will be on 2:1, so thats 2 units to 10g or even 0.5:1 so thats half a unit for 10g.

There are already Carboydrate counting scales, such as the Salter Nuri-weigh range which can help with these calculations but I suppose this could be extended by allowing you to enter your ratio and the device could tell you how much insulin to take although the maths is usually quite easy. Just divide food label carbohydrate by 10 to turn g into CP (and divide or multiply by the portion size if necessary, especially if they've used 'nutrition onfo per 100g' for example) and then multiply by ratio.

Hope that helps and good luck with your device.


sphillips DAFNE HCP
University Hospitals, Leicester
24 posts

HI, I agree with NiVZ, it's often calculating the CP value of the food that's the tricky bit the insulin dose tends to be a bit easier to work out. Having said that as well as working out the ratio for the insulin you would then need to consider adjusting for planned activity and blood glucose at the time of the meal. A calculator type device has already been developed and some DAFNE centres, including Addenbrookes and Sheffield-I think- have worked with DAFNE graduates to try it out, I'm not sure how positive these trials were. I think the first question might be would people find a divice such as this useful?

Toni DAFNE Graduate
Harrogate and District NHS Foundation Trust
2 posts

Hi I also agree

I have a 10g carbs=2units

I find that i using electronic scales work very good becuse you can plate up you food on the scales, also you have to bear in mind you may have a little routine on what you eat i.e breakfast toast, or cereal as you buy the same each week, also you may use the same bowl for breakfast cereal which helps. I find that having practice with not cooking a meal and having to guess what was in it and the portion size, have whom ever cooks it to keep a not of the total of each item and packets you can then work out after meal and see if you got it right. Just look out for the pattern try that food frequent and test a little more if a new thing.

Thats what i did the food i found difficult was jacket potato, porridge, take out like chinese due to sauce they put in. Ow and you may find that you dont need same ratio for breakfast, lunch dinner it does depend.

You will be fine its all trial and error. Good luck