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Insulin on board

G

Georgiepeas

Member
Messages
9
Type of diabetes
Type 1
Treatment type
Insulin
Hi everyone!

I'm a bit confused about this insulin on board business I'm reading about in think like a pancreas. For a start I'm not sure if it only applies to people with pumps because I'm on pens.

It basically says if you eat anything within the 4 hours you still have a previous bolus dose swimming around then when you are working out your dose you should subtract the amount of insulin you still have left from the previous dose. But surely the first one was only covering the carbs you ate previously so why do I need to subtract it? Oh my gosh does anyone understand what I just wrote? Totally confusing myself and probably everyone else!!


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I think it's more to do with correction doses. Say you had a sandwich and injected 6 units, you test 2 hrs later and are higher than you'd like to be. Don't correct as the original insulin you injected is still in your system for 4-5hrs. If after the sandwich you ate something else, inject accordingly. Hope that makes sense ?


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I thought exactly the same thing when I read it. Couldn't get my head round that bit at all. As in theory, if I had a meal and took 8 units, an hour later I could have a mars bar and not bolus for it! I just leave at least 4 hours between carbs now.......I started to subtract the fibre as well until I realised it only applied in America.
 
If people google ..... Accounting for unused insulin It will take you to pdf download that explains how much insulin is still partly active when deciding on insulin dose inbetween the meal bolus to prevent insulin stacking up

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Aye, it's in the book, but, surely the insulin that is still active is there to deal with the carbs you have already eaten? So if you eat more you would still need to bolus for that.
 
Garr said:
Aye, it's in the book, but, surely the insulin that is still active is there to deal with the carbs you have already eaten? So if you eat more you would still need to bolus for that.
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That's correct. If you eat more, inject more. Just don't do any correction doses until all insulin already injected has been used up.


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Yes. Depends how soon after main meal you eat again. If I know I'm gonna have a pudding, sometimes I'll inject for both prior to main meal or sometimes just inject twice.


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I agree it is very confusing. I use an insulin pump and realised that different insulin pumps make this calculation differently. Which is even more confusing.
And even the same pump applies different rules in calculating bob according to your blood readings (>,= ,< ). So I usually let the pump take the decision.



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It's the insulin profile of the insulin you inject that needs to be considered, for example NR it's active up to 5 hours after injecting but peaks around the 90 mins - 2 hours mark where 70% of the insulin is used up(?) and the rest is exhausted over the remaining 2-3 hours.

So if you were to test 2-3 hours after injecting and find your bg was at say 8mmol you would need to consider that the previous injected insulin is still active (IOB) and working to bring your bg down, if you were to eat again at this point and give a corrective dose because of the 8mmol reading then you'd certainly hypo before you next meal-time.

I think this is what they call the stacking effect which iHs mentions earlier, I tend to leave at least 5 hours between meals which is sufficient time to allow for the previous dose to be completely gone, that said if you know what your doing from experience you can inject in-between times.
 
Yes I agree on that but the point I am making is that the stacking effect is not always taken into account in an insulin pump. I'm in my office now and I don't have the paradigm veo instructions book with me, where it is written how the calculation is made. I remember that I found that calculation very unclear and rang the Medtronic customer service. But I didn't get any explanation around the reasons. Sorry if I am talking about insulin pumps and not pens!
For the pens as you said I used to wait 4 hours b4 next injection unless my bg was too high.


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Stefano, my post wasn't meant for you personally but a generalisation of what IOB means and the Stacking Effect, sorry if you thought it was as I was replying to the OP.
 
Thanks guys!
so basically I don't need to worry about it unless I'm making a correction with a bolus within the 4-5 hours that the previous one is active is that right?
That's another thing Garr mentioned about subtracting fibre do we not do that in the UK?
 
your insulin will last 4-5 hours..........its worth testing how long yours actually lasts, for me, its 4 hours, not exactly, but close enough.......

whatever dose you give for your meal can then be split up into equal time portions....you can then calculate what has been used....and therefore allow you to work out how many units are still active when you are considering a snack for example.......

now, if your carb count and dose timing were spot on, then the correction you would usually take at this time would equal the amount of insulin left in your system........

so therefore your snack could be injected for at the normal insulin/carb ratio for that time of day...............;)

the insulin on board matters when the carb count and timing hasn't been 100% perfect and you are either higher or lower than your insulin ob board value would predict........

its tricky but possible on pens..........but I personally try and avoid mid meal snacking, even on the pump
 
Georgiepeas said:
Thanks guys!
so basically I don't need to worry about it unless I'm making a correction with a bolus within the 4-5 hours that the previous one is active is that right?
That's another thing Garr mentioned about subtracting fibre do we not do that in the UK?
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No, it's already been subtracted over here. In America the food label gives total carbs and over here it's the net carbs, with the fibre already subtracted. The way I try to remember if I check online is if it spells fibre as 'fiber' it's probably American so I'll subtract it. Hope that makes sense!
 
Aah ok got it!
Thanks to everyone for straightening that out :)
And thanks for the fibre thing too, I've been subtracting it for a couple of months now oops!
 
I find that if my basal is correct, then my 2 hour post-meal reading will be consistent with my next pre-meal reading, so if I find myself > 7 mmol/l 2 hours after eating, I'll give myself a correction dose.
 
I find that if my basal is correct, then my 2 hour post-meal reading will be consistent with my next pre-meal reading, so if I find myself > 7 mmol/l 2 hours after eating, I'll give myself a correction dose.
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Im getting confused now:confused: Ive never been to any course and I have a feeling im still not 100% there with my insulin.

Sam, so you are saying that if basal is spot on, then your 2h post meal shouldn't be higher than 7? I have always aimed for 8, otherwise I would definitely go hypo before my next meal. Does it mean my basal is too high?
 
No, I aim to have my pre- and post-meal readings consistent with each other. If they are, and my basal is correct, then my next pre-meal reading will be consistent too.

I will give myself a correction dose if my levels are > 7mmol/l in the period of 2 hours after a meal and the next meal.

It could be that your basal is too high, the only way to find out is to do an overnight test.
 
It has to be remembered that Sam eats a low carb diet so that is why his control is like it is. 8mmol 2-3hrs after the bolus is fairly good and hopefully will ensure no hypo by the time the 4th hour has come. Also, everyones fasting level may be different. Mine is 6mmol, whereas others may use 5mmol. If I aimed to be at 7mmol, 2hrs after bolus, then I would need to give myself a fair amount of bolus to achieve that and by the time 3hrs was up, I would find myself going a bit low and would need to eat a snack to deal with remainder of the bolus

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