5 Dynamic ISF

The idea behind dynISF is that ISF isn’t a fixed number but changes as BG changes, e.g. if your BG climbs higher, your Insulin Sensitivity drops and you need more insulin.

FAX-ng is using this, but unfortunately, there are two different versions of dynISF: the one FAX-ng using now, and a newer one that is going to be the new default.

AAPS (Android’s version of FAX) has apparently already replaced the original with the new; while FAX is debating getting rid of the original, or leaving both in with a switch between the two.

5.1 To switch to the new dynISF

Switching to the new formula is simple:

Settings -> Preferences -> Use Logarithmic Formula Enable

You will need to tweak your AdjustmentFactor, as the curve changes with the new formula, so the Adjustment Factor does change as well.

To get to a ballpark AF with Log enabled, just divide by 1.666 what you have now and plug that in .. again, as a starting point

The actual formula is:

F = 1800 / profile.sens * tdd_averages.average_7days * LN( profile.min_bg / ( 120 - pumpprofile.insulinPeakTime + 1 )

Each of the above variables points to the Debug Options screen + variable within it that you would need to use, but again, this will get you only to ballpark: you will want to monitor and tweak AF accordingly.

If you find it’s not aggressive enough, increase AF, if it’s too aggressive, decrease AF.

NOTE: You can use a different value for tdd_averages.average_7days if you want. This smooths out the good and bad days that we all have. The new code actually adds a 14-day value.