Auto calculate QA from BG - let's get it right

Exactly, everyone is different, although I do believe you would still follow the same behavior, so the higher you are the more you would need.............

Its worth working out and recording what 1 unit is doing at varying levels..........

I think that what Simon means by "right" is not that the calculation will always return our BG to its target level (if only!) but simply that any change to the app will support all of the users in ways that they find helpful.

Those that prefer to do BG correction adjustments in their head, or on notepaper, can simply leave the new facility disabled. It would continue to do exactly what it does at present.

For myself, I have found that rigorously applying the full DAFNE formula [QA = CP * QA:CP + (BG - target) * QA:BG] gives me much better BG control than anything I have had before. The best way of obtaining this rigor is to get the app to make the calculation for you. Less brain strain too. I would love for the app to make this calculation automatically, according to the parameters I have specified as being suitable for me. It would definitely be very helpful.

Thanks for your responses so far..

Stew - yes it will be defaulted to off, and people will also need to agree to a disclaimer before turning it on.

It seems there is a need for a few variables:

1. First of all, the point in your target range the app aims for, so this could be changed using a slider to favour the top or bottom of the range.

2. Secondly, different correction factors for different times of day and/or different BG levels. With this I propose setting a general 'expected correction' setting which would be used unless users put in specific overrides e.g. for BG above 13mmol/l or for specific times of day. One question here is should it be done on entry type (Breakfast, Lunch, Dinner) or a specific time range?

Are there any thoughts on the above?

Regarding correction at specific entry types, the simplest way to do it would be, as you described, Breakfast, Lunch and Dinner etc......as the majority of DAFNE grads will only be correcting here. This is the way it should be done. But life is not always as regimented as this and some may find they are correcting in between these times, for whatever reasons, and they might not want to classify them as Breakfast, Lunch or Dinner.

So I would say, at least to future proof the function, you should try and do it by time range. And also be able to set these ranges to suit your personal need as well.....

My tuppence worth.......

I've started work on this and have come across another question: if for example my before bed target was 6.5-8 mmol/l, and I was aiming for 50% of the range between them (7.25 mmol/l) and I'd input a qa:BG lowering ratio of 2.5, there is an opportunity for the calculation to aim for below the minimum target, as follows:

If my BG here was 8.5, the calculation would be (8.5-7.25) / 2.5 = 0.5 which would be rounded up to a correction dose of 1, which if taken should bring the BG down to 6 which is below the minimum target range.

At the moment in these circumstances ive got it taking 1 from the correction dose, but think it may be better to always round down the correction for safety reasons.

What do people think (if you managed to follow my calculations!)?

Well spotted, Simon, and I agree that it is a good idea always to round down when performing positive corrections.

For negative corrections it will also be best always to round down for the same safety reasons. Eg BG 6.0 is below target range, so the calculated -0.5 unit correction should be rounded down to -1 unit.

In view of all that, perhaps the target base used in the calculation should be nearer the bottom of the target range, maybe even the actual low value of the target range. This is safe because any BG even slightly under the target range will cause a negative correction.

I have been thinking about this but from a different angle and that is if I need to take a QA corrective dose or just a QA after CP then I need to calculate how much insulin is still active and swimming around in my bloodstream.

Im a Humalog user and reckon that it has cleared my system in 3 hours but if I have to correct or take a shot for a meal within say 2 hrs of the last shot how should I calculate QA as I will already have QA active in me?

Dont mean to complicate the matter but it is a bit guess at the moment.

my insulinX meter does this, and I beliive a few other do too,, specifically ones that teams up with a pump..........

basically you would just divide up your previous meal time dose by the number of hours you have decided it will last, this will give you a unit per hour, which you can then use together with the amount of time that has passed to work out how much of you previous dose has been used, and therefore what is left..........

my meter then subtracts that from the dose you have worked out for the mid meal snack etc.............

you would never need to correct mid meal though, unless you felt you were uncomfortably high....

I'm pretty much cracked this for the iPhone app - just need some help with some test data to make sure that it's working properly... Here's where you all come in!

If you want to help with some test data, all I need is a table with the following inputs, and expected corrective input:

• Current BG
  
• Target minimum BG
  
• Target maximum BG
  
• % of where to aim for in target range (50% is in the middle of the range)
  
• QA:BG ratio (how much you expect your BG to lower given 1 unit of QA Insulin)
  
• Expected dosage after calculation
  

I would like to participate but I don't understand what information you need......