I have noted in the mornings that sometimes my Tandem pump shows Insulin on Board even after 8 hours in sleep mode. Tandem says sleep mode only varies the basal, without boluses. So I asked our Regional Rep and got this reply:
“When the pump is in sleep activity you will only have basal rate changes, no auto bolus. However, IOB displays any insulin delivered above your set baseline basal, including any insulin that was automatically delivered via basal adjustments for predicted highs. For example, if pump is in sleep activity and your programmed basal is 1.0 units/hr but your blood sugar is rising and the pump increased your basal to 1.5 units/hr for an hour, you would see 0.5 units displayed in the IOB.”
Sometimes I’ll wake up in the middle of the night, check my pump, and my basal will be twice as much as programmed. It doesn’t give the insulin nearly as quickly as an auto-bolus… but it adds up!
I found this Tandem post helpful to make sense of the Control-IQ IOB! Insulin on Board (IOB)
A bolus can fix a high BG much quicker than an increase in basal. Yet all the automated pumps - Tandem, Omnipod5, Loop, etc. - use basal increases like this.
(I know some of them also use bolus, but they all do basal increases.)
I guess the thinking is that it’s safer and it can be turned off if it looks like it was going to be too much. It’s easier to fix an automated basal increase if it turns out to be a mistake. But a bolus can’t be removed.
So I guess that’s why all the pumps do it that way?
When I have a high BG, and I am doing it myself, I don’t use basal. I just bolus that thing away
That makes sense! Control-IQ does do auto-boluses when not in sleep mode (up to one an hour, per the Tandem website). Sometimes helpful…
I wish there was an auto-bolus notification. Start the bolus pending – but give me a notification and a minute to possibly cancel it! The number of times I have been on the rollercoaster going low, then “rising fast” because of the low treatment, getting an auto-bolus, then going low, then “rising fast,” then getting an auto-bolus… Oof.
Next time I should get smart and use exercise mode (which I forget exists) or just turn off Control-IQ for a few hours after the second bad auto-bolus.
Completely understand this and is one of the reasons I use sleep mode all the time. One of the the craziest things is exercise mode. The last I want is an automated bolus when exercising.
The pump does haven’t enough information to know exactly what is going on.
I’m just 2 months into Tandem (from Omnipod) and while much still adjusting am making improvements with my educator team. They recently suggested the counterintuitive exercise mode at night as the sleep mode I was getting low drops,
So far it’s keeping a better plateau just having to remember to activate every night.
Oh we have been fine tuning different basal rates, plus also correction factors, insulin to carb ratios. There’s a lot of factors as we all know, not to mention for me, widely variable eating times.
Oof.