Correction dose help please

sorry if this is a bit vague as an answer -- but it looks like all your calcs look ok ---the only thing I would say is that when BG is around the 12 level -- I find I need less to lower to target than if BG is 14-16

we are all different as well so it is impossible to say if that dose was correct

ChrisM28 said:

Thanks himtoo, don't worry about vague any and all thoughts gratefully received. The dose was too high even with the dextrose he was on 4.6 by 8pm. Could you think about some more of my sums for me please? The 3 dextrose were 9C, evenings we're using 1:6 so the dextrose should have used up more than a unit of the 3 he took. Is that the way I should be thinking?

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Hi Chris, Insulin sensitivity factor (ISF) is essentially the inverse of your I;C ratio. I:C is 1:6, so 6g of carbs should raise BG level by roughly the same amount as 1u will lower it. 9g of carbs should therefore raise his glucose by roughly the equivalent of 1.5x the amount 1u would drop him.

There are a couple of ways of working out correction dose. Mathematically, by estimation followed by fine tuning and experimentally.

Experimentally, you make sure your blood glucose level is at about 9mmol/l and running steady, with no carbs on board, then you administer 0.5 or 1u, depending on which you feel safest with. You give the insulin 5 hours to see how much you come down by.

Mathematically, you can estimate using the rule of 100. To do this you take your total daily dose, which includes basal and boluses, add them up to create your TDD, then calculate 100 divided by this number. That is the estimate of what one unit will drop you.

e.g. Basal = 20u, breakfast =7u, l;unch = 8u and dinner = 10u, gives you a TDD of 45u.

The correction factor (also known as Insulin Sensitivity Factor) is 1u: (100/45), which equals 1u:2.2mmol/l

In theory, you'd see a drop of 2.2mmol for each 1u of insulin.

This is an estimate, and you should always try and check it, as you'll probably find that it is not exactly that number as it assumes that you have your doses set up correctly. Likewise, as your levels get higher (typically above about 12mmol/l) most people find that their correction factors are out and they need more insulin to achieve the same drop.

ChrisM28 said:

Still 1.5 hours to go (assuming 3 hour action time) 50% of insulin still OB 1.5U which could drop 3mm so took 3 dextrose.

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Be very careful in how you use action time in these assumptions. Novorapid typically lasts for a lot longer than three hours but has a long tail. Even a dose of 2 or 3 u can hang around for as much as 6 hours, but the peak is from 0.5-2 hours.
This graph should explain it a little - Novolog is the US name for Novorapid:

ChrisM28 said:

Does this mean he's sensitive to the insulin??? Given that he's on an I:C ratio of between 1:4 and !:6 I thought it meant he was insulin resistant.

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I suspect what it means is that his basal and ratios aren't quite what you think they are and you may need to go back and re-evaluate basal (via a basal test https://mysugr.com/basal-rate-testing/) then take another look at ratios and ISF.

If you are on Novo then go for the Novopen Echo which does .5u

I was told 4 years ago to stop using Novopen3 and go to the 4. If you look on the .co.uk site they will give you the PIP codes for Red or Blue pens. If you need more than 30u for basal (if on Levemir/Tresiba) then get a Novopen5
NovoPen® PIP Code
NovoPen® 5 Blue 393-6465
NovoPen® 5 Silver 393-6473
NovoPen Echo® Blue 368-7076
NovoPen Echo® Red 368-7365