When bolusing and you're within range and you've got IOB, it doesn't subtract the IOB from the bolus total. According to the manual it's for "reference". Do you manually subtract the IOB amount or do you go with the bolus total the pump recommends?
I've found that it's best to go with what the pump suggests. It normally knows what it is doing Mathwise.
I go with the bolus total the pump recommends. I do NOT manually subtract the IOB amount.
If the pump doesn't subtract IOB, then I don't manually. (This is for my 5y.o. son.) I may reduce the insulin I'm giving if he's on the low end of his range and is getting ready for a physical activity, but to me that is just increasing his I:C ratio at that time, not adjusting for IOB, but one could say it is the other way. Potaeto, potahto.
From what I can tell, the IOB is not subtracted when you are giving a bolus to cover food - so if you are using Normal, ezCarb, or Combo. This is because the assumption is that your IOB is to cover something you needed previously - you will still need the full amount of your bolus to cover whatever you are about to eat plus the IOB to cover the previous event. When you are using ezBG (to correct for a high reading), the IOB is subtracted for you on the pump so that you don't over correct.
The IOB is not automatically added... it's given to you as a reference to use as you wish... I never use my IOB because if I take it into account, my sugars will go high... perhaps my body uses it faster... not sure.... but I just bolus based on current correction + carbs.... I neglect IOB
Dana is absolutely right. IOB is only an issue if you are correcting a high reading. If you are covering for carbs, you need the whole amount to cover what you are eating. You can also adjust the time frame your pump uses to calculate IOB. If you seem to use insulin faster...you can shorten the time frame. :-D