Basal Testing in Closed Loop!

Here’s a great way to test your basal rates overnight while in Closed Loop.

Keep your Loop closed and set a target override similar to the one in this screenshot.  A wide target range will provide “safety bumpers”.  Loop will only give a correction dose or suspend basal if it predicts you fall outside of this wide target range over the future 6 hours.   Leave your glucose safety limit alone, and set the lower end of your override target range 10 to 20 points higher than your glucose safety limit.  Set the upper end of the range as high as you’re willing to tolerate overnight drift.  For example, while keeping your suspend threshold at 70, set the lower end of the correction range at 90 and the upper end around 180.

  • If the prediction remains within this wide target range, Loop provides your scheduled basal
  • If the prediction goes above or below target, Loop corrects to the mid-point of your target range
    • For this example, it will aim for 135 when correcting
    • If prediction returns to be within range, dosing returns to your scheduled basal rate

Using a target override for this testing will ensure that your correction range returns to normal at the end of the override duration.

Of course, as with all basal testing, you need to

  • Be within the correction range when you start,
  • Have no carbs on board (COB)
  • Have no insulin on board (IOB)
  • Refrain from exercise
  • Not be on the first day of a new sensor (when accuracy can be off)

Overnight is a great time to check basal, but most of us are going to bed with COB due to our evening meal.  The solution is to set up a future override.  Set up the override before you go to bed and schedule it to start when you think your meal will be fully absorbed.


Absmindedprof shared this method of basal testing using closed Loop. (Link below). Used with permission.

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