Tandem ControlIQ and Correction Boluses

I’ve been on CIQ for about 1 month. The best thing about it is the overnight stable blood sugars. If that was the only benefit, well worth it for me. But there is one thing that really frustrates me and I don’t quite understand is exercise mode and correction boluses.

The target in exercise mode is140-160 which for me is fine since as I tend to trend low during physical activity. This weekend I was out hiking and running low so took some glucose which quickly raised my BG. Then as normal it levels out and slowly begins to drop as I continue my hike. So the frustrating part is my BS was going up so quick the algorithm calculated that I was going to be out of range and gave a correction bolus. Which was the last thing I needed and then caused me to crash.

It’s done that a couple times and makes me not trust exercise mode. I wish exercise mode didn’t do correction boluses (fine with basil adjustments). It just seems obvious that glucose use during exercise is going to cause problems with the algorithm.

Curious how loop handles exercise and correction boluses?


We manage that problem by injecting Lantus for 40-50% of basal needs and just unplugging from the pump during exercise. But I am sure the loopers will be by shortly with a loop answer.

Hmm, Control-IQ has a timing thing where it can’t give a bolus within a certain amount of time of any previous bolus.
So, try and give a super small bolus before exercising and see if the timing of it will keep it from giving the autobolus.
The other option, try and do it in sleep mode? I stay in sleep mode all day, and while it does increase my IOB slightly for a higher BS, it doesn’t give a bolus, so I don’t really have issues with going low.
Also, if I do move a bit lower for my BS, it is SLOW, and I can usually adjust for this easily, as long as I somewhat pay attention.
I know, not the best solution.
The other option, like mentioned, is to unhook the pump so any bolus is not actually given during excersise. This is sort of dangerous in case you completely forget.
Or just stop insulin delivery?


I’m running LOOP rather than CIQ, but I experience the same problem. A glucose correction provokes them to give more insulin to treat an unexpected rapid rise. In LOOP my mitigation is in 2 parts. One is I tell them I’ve taken 4g or 8g with a carb duration of 30min, so that the rapid rise isn’t “unexpected”. The second is I run a temporary override (called Just Stop, with a big red X as the icon) that says for the next 90 minutes I’m extremely sensitive to insulin (need 10% of normal) and I want my BG in the range 150-180.

With CIQ what I’d try is to turn off CIQ, set a temp basal of 0 for 60 minutes, and set an alarm for 60 minutes to remind me to turn it back on.


Good idea, I hadn’t thought of that!![quote=“Hammer, post:3, topic:9929”]
The other option, try and do it in sleep mode? I stay in sleep mode all day, and while it does increase my IOB slightly for a higher BS, it doesn’t give a bolus, so I don’t really have issues with going low

I’m in sleep mode all the time except when I exercise, but I’ll experiment with it a little more.


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Wish control iq had that feature.

I’ll probably just stop control iq and use a temp rate in the future like you said. I was trying to do everything with the ciq features.

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I’m using Loop Auto-bolus branch. I also use a temporary override for running, walking or whatever activity I’m engaged in. Depending on the intensity of the activity, my current BG, BG trend, carbs, IOB, I activate an override for a user configurable duration, eg., 2 hours. For example, walking might be a TB of 70% (of normal basal) with a target of BG 90-100 (these are both user configurable). For running, it might be a TB of 30% with target range of BG 100. I’m usually lower than 90 during exercise so really, these overrides ensure I get ZB. Hwr, if I take some carbs during exercise or start to spike, Loop will auto-bolus based on the override TB and target range. This usually ensures I don’t go too high. Sometimes the auto-bolus is insufficient, and I will manually bolus 0.2U (using my Apple watch) or some small amount depending on what I’ve eaten, how much more activity I have, BG, etc. I also will disable the TB override about 1-2 miles (running) prior to ending to offset the post run spike, and maybe even give a small bolus of 0.5U if I will be refueling right away post run or I have an up BG trend.


I am a believer in doing all of this manually for exercise. The algorithms are built for the masses, not for you personally.

If you are able to test while hiking (I can get you hooked up with a strip holder), you will be able to do much better manually, after some practice.


I agree with you on that. Tandem knowing they were building exercise mode for the masses, and designing a correction bolus feature just seems problematic. I mean that’s when insulin sensitivity and absorption is at the extremes.

I’ve seen the pictures of your strip holder, very cool. :sunglasses: I appreciate the offer very much and will keep it mind.


Sure, just let me know. It’s free.

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