Multiple hypos overnight even with Basal suspended by pump most of the night -why and what to do?

I’m hoping the brains trust here can help me. I have been a T1 for for over 25 years. I started on Tandem x2 a year ago, and have found Control IQ works really well. I am used to having hypos but these have lessened a lot on the pump compared to MDI, and overnight hypos are rare now. However, in the last 3 weeks I have had a few, and then for the last 2 nights, I have had multiple in one night (3, about 2-3 hours apart, and throughout the night). My pump alarm wakes me up, and I treat it with glucodin powder, but the usual amount has seemed to not lift the BG as fast or as much as usual, so I have ended up doubling or tripling the amount on my second hypo each night. I have also followed up the glucose with a longer acting carb, which I usually don’t need to do, now I’m on the pump. Control IQ has suspended the insulin for most of the time before and then after the hypos, apart from delivery of a small amount of basal insulin in a window between suspensions when my BG rose slightly, but then back down it drifts, Control IQ suspends, but 2-3 hours or more later, another hypo. I can’t understand:

  1. Why this sudden change in pattern? I have not been exercising more than usual during the day. (although I have been exercising normally but more days in a row than normal as I am off work right now). I am not sick or stressed, and I have been eating normally. I am peri-menopausal - so maybe something is changing hormonally that I don’t know about.
    Is my natural glucagon response not working right now?

  2. After the first night, I changed my settings by halving the basal throughout the night and increasing insulin sensitivity ratio. For 2.5 hours between 2-4:30am, I set the Basal to 0, which I have never done, but is was on 0.1 and I couldn’t go lower - I still had a hypo around 4am!! I also changed the settings for the 3 hours before bed - My BG has been plateauing too high after dinner and before bed, so much so that my pump asked me to check my site and tubing. So the basal was increasing at this time, and one modest correction dose given. About 1.5 hours after that, and just as I’m going to sleep, I see it heading down which is normally good, but it looked like it was heading down too rapidly with the pump partially suspending, so I ate some long acting carbs both nights before sleeping- however this did not allay the first hypo an hour or so later

So now, what to do tonight? Basal has been suspended most of the night anyway, but perhaps I should set it to 0 for longer?

Any ideas?
Hopefully this will pass. . .and return to normalcy

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I don’t know for sure, but my first thought is that it might be a delay in your insulin absorption. Like the insulin from earlier boluses might be absorbed much later than what you are used to.

Perhaps you can try moving your pump infusion to a new place that you have never used before, just as a quick check to see if it makes a difference.

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Here is info that may apply.

Ah, okay, thanks for that possible idea, etc I hadn’t considered. I have changed the infusion site before I read your reply, although not to a completely new site I have never used. Let’s see if there’s a return to more normalcy. . .

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Thanks for this info - this is clear information, which is hard to find on this topic. The peri-menopause is definitely a roller coaster ride with unpredictable effects.

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Sounds like your basal requirement has decreased during the night.

That is an enormous change. It’s in a safe direction, but it makes me think that it’s time for some proper basal testing and adjustment to get a good foundation. Then actually test insulin sensitivity to get that right, followed by testing the insulin:carb ratio. Granted these values will continue to change, but at present it’s acting like they are way off.

Again, it looks like the basal, ISF, and CR all need to be newly calibrated to match your body’s current insulin requirement. It’s a nuisance that it changes out from under us, but all of us insulin-dependent diabetics are standing on a flying carpet, not solid ground.


I changed the site, as I said about 24 hours ago (at about 7:15pm just before the new G6 dexcom warm up which you see on the first graph), and last night was better - I only had 1 hypo.

I still want to avoid that too tonight. I am already on 0.1 basal between 9 and 2pm, and other than a few modulations, I still hypoed after a couple of suspensions. I can’t go below 0.1 unless I go to 0, which seems crazy. Last night, after dinner and before bed was pretty stable and not a lot of CIQ boluses or increase in Basal, so I don’t think there was a build up of delayed absorption from previous boluses.

I am going sky high tonight because I severely miscalculated my carbs at dinner, so ignore that for now.

I think I’ll just leave my settings as they are and see what happens tonight.


That is a move in the right direction. :+1:

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But that is the available work-around. For instance, schedule the basal to alternate back and forth between 0 and 0.1 on, say, an hourly basis to get 0.05 effective.


There’s this observation about CIQ:

That seems to match your experience.

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Thanks all for your advice and reassurance. I have reduced my overnight basal to almost 0, and have avoided hypos for 2 or 3 nights now, without being too high in the morning.
8:30-10:00pm Basal 0.2
10:00-12:00am Basal 0
12:00-2:00 Basal 0.1
2:00-3:30 Basal 0
3:30-7:00am Basal 0.4

It is surprising to me that there has been this big and quite sudden change in my insulin sensitivity, and I have never dropped to 0 basal at all, let along for several hours, unless I am exercising, or my pump suspends.