Long active insulin times?

My pump is the 670g and my active insulin time (AIT) is 5 hours and 30 minutes. Does anyone else have such a long AIT? When I started on this pump at the beginning of this year, my educator started me on the standard AIT. But my endocrinologist and I have found over time that my insulin does remain active for that long. That is, my BGs continue to go down absent any other factors that would cause a decrease. That happens regularly for me.

With such a long AIT, I’ve been wondering of that would affect any pump settings and checks. For example, since the insulin lasts that long for me, does that mean that my “max delivery time” check should actually be done over a longer period of time, since it may take longer for a bolus to take effect?


Hi Jack @stansbuj, I have not used the 670-G so I’m not truly familiar with the algorithm. You can check if it properly adjusts for your set AIT with a piece of paper, a pencil and grade school arithmetic.
I use a t-Slim x2 and its algorithm does properly take into consideration my IOB when I have the duration set beyond the default setting.

Thanks Dennis. Without knowing the 670g algorithm, I’m not so sure it is easy to calculate. My endo and my Medtronic rep are convinced that the pump can’t handle such a long AIT based on my readings.

The active insulin time and its algorithm are simply to prevent stacking of correction boluses. When you use Bolus Wizard, it gives you carb boluses regardless of current active insulin. But, for your correction bolus, it multiples your current blood sugar(anything over 120mg/dl) by your “insulin sensitivity factor”, then subtracts the active insulin amount from your correction bolus.

BOLUS = ( Carbs x Carb ratio) + ( ( ( BG - 120 ) x Insulin Sensitivity Factor ) - Active Insulin)

Apidra, Fiasp, and Novolog are faster acting for most people than Humalog