Lets say I have breakfast around 7:30 and I'm hungry for a snack around 10:30 and I decide to have a snack but still have insulin on board. Do I just subtract what's on board from what the pump is telling me to give?
What kind of pump? I think that the Medtronic "wizard" cuts that IOB out. The other thing to consider is that if you have IOB, you may also have FOB, or "food on board" which the insulin is sort of aimed at? If you are pretty confident in your ratios, I'd say bolus away.
It is really hard to answer your question. I believe that the Ping tracks Insulin On Board (IOB) and if you use the wizard, it will subtract off for remaining IOB. But the features on your pump can be turned on and off (like IOB), so I really can't tell you without knowing more about your setup. You can look up some of these questions in the Owner's Booklet.
One Touch Ping. Makes sense, thank you.
thank you.
Yes, the Ping keeps track of IOB. Accuracy of course depends on the settings you have... insulin duration, etc.
Generally, in that scenario, I would just bolus the amount the pump calculates for the new carbs/snack. This is based on assuming that any IOB is correctly matching remaining breakfast food (FOB or 'food on board') and reduction of current BG.
But as others suggest, there are other factors:
Is your current BG lower or higher than you'd expect, based on your breakfast ?
What food did you have for breakfast - mostly carbs that are often gone in 3 hours, or fat/proteins that are still being digested ?
What is/was/will be your activity level ?
Is the IOB only due to your breakfast bolus, or did you do a correction ?
All other things being equal (ie correct ratios, correct carbs, BGL in target range), yes, you would subtract IOB if your pump does not do this for you. Your IOB will depend on how long your insulin acts for, typically 3-4 hours for adults.
So if you do a BGL, and you are above your target, then the IOB is still active returning your BGL to target levels, and you should NOT subtract it. If your BGL is at or below target, then you have potentially had too much insulin, so subtract it.
Or, adjust your active insulin time!
It's a mess! Try ManageBGL.com to visually see where your BGL is heading, and fine tune your ratios.
As mentioned yes the Ping tracks the IOB and will list it, but if you bolus for the snack using ezCarb wizard it won't deduct the IOB from the insulin needed to cover the carbs in the snack.
The pump/tool should only subtract IOB if you give it a BGL at the same time. Otherwise it has no way of knowing if you're over or under your target given the insulin action time.