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Active insulin and minimed pump
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Active insulin and minimed pump

I am on the minimed pump with novolog and i tend to eat small meals throughout the day rather than large meals.  This makes it difficult to gauge whether I bolused enough for my meals, since my insulin boluses overlap, so I can't follow the 140 after 2 hours ideal.  Does anyone have any advice on how to estimate how much your bs will drop with however many units of active insulin remaining?  One unit of insulin drops me about 60 points when i am high, but when I have 1 unit of active insulin remaining from a previous bolus, i usually don't drop all that much depending on how long ago the bolus was. And if i am high and enter my blood sugar into the pump and punch in 0 carbs to estimate a correction bolus, the pump will subtract the units of active insulin from the estimated correction units, resulting in an insufficient amount to bring me down to my target range.  Any advice??
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Hi Snowbunnyy,
Nice to hear your voice again.  As you know we're all volunteers here, so check out our ideas with your CDE or endo.  This msg is long cuz it takes a lotta words to decribe & justify what I'd like to share with you.  Hope it's helpful.

I'm a pumper and use Novalog, too.  I use a Cozmo pump, but the concepts are the same.  I read an article (I'll try to find the reference; I know it was done by John Walsh who also wrote that great book, Pumping Insulin) that surprised me, but I applied its premise & BINGO! it helped me a LOT.  

His research indicated that for the vast majority of us, one unit of Novolog will have an effect for about 5 hours (he cited a range of 4.5 - 5.5).  That is a LOT longer than I had programmed my Cozmo for, but I also was struggling with lows, then highs that seemed to fit the pattern of "cuased by overlapping boluses."  I believe that the Minimed pump does not allow you to set the duration, which does complicate things.  Some of the newer Minimed pumps DO account for insulin on board, but last I read, they did NOT use the 5-hour rule.
Check your manual to find out for sure.  

If a pump uses SHORTER than 5 hours, then the pump with "think" there's less insulin still working than there really is.  If a pump uses LONGER than 5 hours, it will "think" there's more at work.

Here's a way to figure things out using the 5 hour rule.

Let's say you bolus 1 units at 12noon either to cover a snack or to cover a meal and a high.  Let's say your insulin does, in fact, work over a 5 hour period.  That means that

at 12noon:  1 unit is working  0 units "used up already"
at 1pm:  .8 unit is still working; .2 units "used up"
at 2pm: .6 units is still working; .4 units "used up"
at 3pm  .4 units is still working; .6 units "used up"
at 4pm  .2 units is still working; .8 units "used up", and finally
at 5pm: 0 units still working; 1 unit used up.

So, if you wanted to have another small meal at 3pm, you would know that you still have .4 units still churning away in your system.  Subtract .4 from any bolus and you'll be about right.

I no longer focus on the "140 after 2 hours" because I know that a meal with noticeable carbs will get worked on for 5 hours. From what I've experienced so far, it's close to impossible for my current balanced way of eating.  Why?  At 2 hours, I'll always have 60% of my bolus still working.  If I'm <140 at 2 hours, I'd need to snack again to prevent a low.  That seems like a recipe to take on extra calories.  FOr now, I notice my 2-hour number AND I notice how much insulin is still working.  If that amount will bring me to my goal number within the remaining time, I leave it all alone.  If I misguessed the bolus, I still REDUCE the correction amount by the amount still working.  

Over time, I pay more attention to the averages on my meter, my ability to avoid dangerous lows and dangerous highs... and my a1c.  All those things are looking better since I've been applying the 5-hour rule.  

This all may sound very complicated, but if you think about it a while and chat with your CDE and/or endo about it, perhaps you'll see similar positive results.
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I am also a volunteer, and not a physical. My daughter is now on the minimed 712, she used to be on the minimed 508.  If you have a minimed 507, 508, 512, or 712 pumps you can upgrade your pump via the pathway system threw minimed to a 515 or 715.  One of the features on this upgrades pump is that you can adjust how long the insulin stays active in your system.   This would help you out with your situation. If the pump you r are using now has the Bolus wizard it will take into account what you already have active from your last meal, it will take into account what is active and minus that out so it will not give you a full dose to avoid you from going low and to keep your blood sugars in range.
I would suggest talking to your endo or CDE. what we do is check her blood sugars for 3-4 days and fax her numbers along with what she has eaten so that the endo can adjust her ratios and basal.  Using the bolus wizard has taken my daughters A1C from 7.9 to 6.8.  

Check out minimed website


Good luck
Hello I have the MM 715 and this one does have a setting to be able to work with "ACTIVE" insulin times. It helps to avoid the overlapping, or stacking. You must set the Bolus Wizard Set up.
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