If you use a rapid insulin there are basically two ways of managing in.
The method you are using is a fixed dose which you vary according to glucose levels before meals. This can work well but only if you eat the same amount of carbohydrate for each meal . This would include all carbohydrates including those in milk, vegetables, fruit as well as the more obvious ones in starches like potatoes, pasta and rice,
I started with this method and was given a fixed amount to eat at each meal. I weighed, measured and calculated. It became relatively easy to see that for me 1U of insulin 'covered' about 10g of carbohydrates (for me slightly more at breakfast and lunch than at dinner we all differ in this)
I'm not in the UK (in France) and was taught to have 1/2 plate veg. 1/4 plate starch. 1/4 ''protein' plus a fruit and some dairy
I still tend to stick to this pattern but moved on to changing my insulin according to what I wanted to eat; so if I had a smaller meal with fewer carbs then I would take less insulin, if I ate more then I would take more.
(that's the simple version, as you do it more you find that there are exceptions, especially if you eat a very low carbs meal when you may find that you need proportionately more insulin ; record keeping helps a lot.
Have a look at this online course which teaches you how to adjust your dose.
http://www.bdec-e-learning.com
Counting carbs is different to adopting a low carb diet; the number of carbs and calories that anyone needs varies according to their activity levels, gender and age. There is no one diet that will suit all. There are Olympians (and a Commonwealth games cyclist) who use insulin. I need far fewer carbs than they do as I'm much older . On the other hand, I walk or run at least 5 miles a day so I probably require more than someone of the same age who is sedentary.
One size/diet would not suit all.
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