Just download and read this document which is the main point of DafNe regarding Carb Counting and Insulin adjustment ..
Carbs count e-book – An introduction to carbohydrate counting and insulin dose adjustment.
https://shop.diabetes.org.uk/usr/downloads/Carbs-Count-2012-reduced.pdf
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I've been a Type 1 for 43 years, and recently decided to get up to date with what is available on the internet, and this is really good.
You need to know what your IC ratio (Insulin to Carbs Ratio) is for EACH meal, and record all your BG, Carbs etc and you will find it is relatively easy to control your BG ... then ... no complications in the long term ...that's me!