Carbs to insulin ratios.

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marcus1979

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Type 1
Please could someone help. My nurse says 2.5 to 10 ratio but I’m struggling to work out the maths. Can someone really dumb in down for me or is there an app that will do it. Feel like I’m failing here.

Thank!
 
I think that is 2.5 units of insulin to 10g of carbs.
In "them there olden days", the diabetes community/doctors came up with the concept of a portion of carbs which was equal to 10g.
The idea was that you looked at a plate of food and split into into portions of 10g of carbs - you were to learn how many chips make up 10g carbs or how many cups of rice or how many slices of bread. I believe this was before it was common to have the carbs per 100g on most packets of food and people learned to use calculators. But some DSNs continue to use the 10g carb portions.

As an engineer, I find it easier to think of how many grams of carbs need 1 unit of insulin. So I would think of your ratio as
1 unit of insulin for 4g of carbs.
 
marcus1979 said:
Please could someone help. My nurse says 2.5 to 10 ratio but I’m struggling to work out the maths. Can someone really dumb in down for me or is there an app that will do it. Feel like I’m failing here.

Thank!
Click to expand...
2.5 units of insulin to 10g carbs is only really doable if you’re having all your carbs in multiples of 10, otherwise the maths gets too complicated.
It’s the same as saying 1 unit of insulin to every 4g of carbs, which may be easier, because if you count up your carbs and divide by 4, that gives you the number of insulin units you need.
For example, if you calculate a couple of slices of toast as 30 carbs, divide by 4 (use a calculator if necessary) and you get 7.5 units of insulin. Assuming you’ve got a half unit pen, this is doable, if your pen only does whole units, you’ve got the option to round up or down to 7 or 8 units, depending on how you think the carbs will affect you. (Sometimes it’s more of an overall gut feeling than a strict mathematical calculation)
Edit. @helli types faster than I do!
 
marcus1979 said:
Would it be ok to use the 1 in 4 though, would that give me enough Fiasp?
Click to expand...
1 in 4 is the same as 2.5 in 10g.
If your nurse thinks that is enough, it is fine.
It is always a good idea to keep an eye on your blood sugar levels when you change your dose ... but remember Fiasp can take 4 hours for your body to use up the full dose.
 
marcus1979 said:
Would it be ok to use the 1 in 4 though, would that give me enough Fiasp?
Click to expand...
1 to 4 ratio is exactly the same as 2.5 to 10.
If you split the 30 carbs in my example you get 3 lots of 10 and if you allow 2.5 units for each of the 3 lots of 10, you get 3 x 2.5 which equals 7.5. (The same as if you divided by 4 and allowed 1 unit for each lot of 4)
 
helli said:
As an engineer, I find it easier to think of how many grams of carbs need 1 unit of insulin. So I would think of your ratio as
1 unit of insulin for 4g of carbs.
Click to expand...
Yes, that's how I'd look at it too (it's what most bolus calculators want as the ratio: the number of grams per unit). And the calculation is straightforward, it's 10/2.5:

2.5 units for 10g​

divide everything by 2.5 gives you

1 unit for 4g​
 
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