insulin to carbohydrate ratio

dpashley said:

I am making a website for a competition to help young diabetics. What I am making is a system that will take reading for insulin to carbohydrate ratio, blood sugar and carbohydrate portions to give recommendations on the amount of quick acting insulin to take to reduce, maintain and raise blood sugar.

What I need to know is what effect does your insulin to carbohydrate ratio could have on my calculations? I am on a ratio of 1:1 and 1 portion of carbs will raise my blood sugar 3 and 1 unit of insulin will lower it by 3. So what will other ratios do to it such as a 1:0.5 or 1:2?

Thanks

Dan

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If I understand your question correctly, the two ratios are independent of each other as far as I know. So knowing that someone needs 1 unit of insulin for 5g carbs does not tell you how much this will raise or lower blood sugar. You need to know the individual's insulin sensitivity factor (which in your case is one unit to 3 mmols/l.

dpashley said:

so instead i should get my website to ask for insulin sensitivity not ratio?

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You'd need both if it's going to work out bolus doses.

How much 1CP raises BG depends on a few things, but the usual lie-to-children you get is that "BG increase = carbs eaten". Assuming average weight (and thus blood volume), 1 CP should increase BG by 2-3 mmol/l.

The usual "insulin to carbohydrate ratio" is how much insulin is needed to keep BG within range after meals. 1u : 1CP means that you need to have one 1u insulin per carbohydrate portion to keep BG within the acceptable range. Most people will have a ratio ranging from 0.5u:1CP to 4u:1CP

The other thing is insulin sensitivity - how much one unit of insulin will lower BG by. The usual starting estimate is the rule of 100: Divide average total daily insulin (basal + bolus) by 100. For example, if you're taking 10u of basal insulin and 5u rapid acting insulin with each meal, you'd expect one unit of insulin to lower your BG by 100/25=4 mmol/l

Finally, I'm not entirely sure what you are trying to do. Advice on doses in general? Something like the table in this leaflet?
Or immediate advice for meals after taking a BG reading (like the Insulinx* meter does)?

* Sorry, can't link to the website since it seems to have disappeared. All that Google turns up is this rather less exciting product page.