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Medtronic pump active insulin time?

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skipbifferty

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Hi everybody, hope you're enjoying the summer at long last. I'm using a medtronic 754 insulin pump. The other day I bolused for a meal - about 4 units I think - and I had no active insulin (showing on the pump) at the time. I've got my active insulin time set to 4 hours (novorapid) and three hours later it was definitely under 1 unit less, ie. less than 1 fourth of what I originally injected. Does this pump simply divide the active insulin time by the number of units or does it do something more complicated like have a peak (as in the real world) and then a valley? Perhaps I misread the pump at the time but I'd be grateful for the input from this forum.
 
Just to add, when I was looking at the insulin time I did take into account the time it takes for the bolus to finish being delivered - and it didn't make sense either with the time I bolused or the time it finished.
 
Ok, today at 1.30pm I bolussed 6.5 units with no active insulin at the time. Checked at 2 hours and it was slightly under 3.2 which I thought was about right. Then at the 3 hour mark it was definitely showing under 1.2 units. 1.2 X 4 = 4.8 units so that's about 1.7 units unaccounted for! Does anyone know what's going on here?
 
Not sure with that pump, but my accu chek only shows the correction doses of active insulin. so if I bolused 6 units for a meal, those 6 units would be allocated for against the meal as needed but active insulin would show as 0. However if I needed 6 units plus a 1.0 correction, then active insulin would show only as the 1 unit correction slightly decreasing over the active time of the insulin.

Sent from my GT-S5360 using DCUK Forum mobile app
 
Thanks for the reply Brett. I've just found out the answer. Medtronic and Animas are supposed to use a 'curvilinear' graph whereas the Omnipod and Cozmo use a 'linear' graph. In the words of another pump user (on the net), 'The formula generated is an approximation since the pump companies keep their formula a tightly held secret!' (http://forums.childrenwithdiabetes.com/ ... hp?t=44485).

This article explains it in detail: http://www.diabetesnet.com/diabetes-tec ... n-duration.

For your pump, Brett, it probably doesn't matter too much but I think, for people with Medtronic and Animas pumps, it's important to be aware of this. I probably relied on the number too much anyway because I was always aware that the active insulin time is different for people anyway. I wrongly assumed though that it was a linear calculation.
 
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