Sleep – better with a loop or not?

People talk about improved sleep with closed loops, as the system continually adjusts your pump’s basal insulin flow to keep you within range while you sleep. But it wasn’t something I was really conscious of before today.

In fact a week ago I was talking to my endocrinologist about how I was coping on the loop, and one of the things we talked about was quality of sleep. At the time I said I hadn’t really noticed a difference, but my wife was getting better sleep because my CGM wasn’t waking her with overnight alarms any more. I generally sleep like a log so the warnings disturb her more than me.

However last night I had a hypo, even with a closed loop.

Overnight hypos

No loop is perfect all the time, and it seems the combination of extended exercise yesterday, combined with a CGM transmitter failure last evening (with calibration of the new transmitter at only one level before I fell asleep) left the loop struggling with dropping glucose levels overnight. It did the right thing and turned my insulin off as soon as the BG started dropping, but I needed more carbs to fight the drop.

I woke up very groggy at around 3:30am, and realised after a while that I was hypo. A fingerprick showed that I was at 3.3 mmol/l (this is the lowest I’ve been for a long time, although not as low as some of the hypos I’ve had over the years). This test also recalibrated the CGM. So I scoffed some glucose tabs, then headed off to the bathroom then back via the kitchen to grab some longer-acting carbs.

I went back to bed and quickly fell asleep again. I knew that if my BG rose too far while I slept then the loop would control it. And it did: I later woke up at 5.3 mmol/l, and the CGM trace showed the rapid rise from the carbs was flattened off by some extra insulin.

All good: the loop had done it’s job and helped me fix the hypo smoothly, so now I could get on with my day, right? Well, not quite.

Noticing the difference

It was at this point I noticed something about life with the loop that I hadn’t really been aware of in the last 4 months without overnight hypos. I was sapped: I had very little energy and did not at all want to get up. That overnight low had really exhausted me! Luckily it was a Saturday morning and I could take it easy. I did get some breakfast which I ate in bed, and eventually got up and got on with my day.

I realised that I used to feel like this a lot. Not that it felt like a problem back then: it just felt “normal”. I hadn’t noticed with the loop that my sleep was dramatically better or that I had more morning energy, but when that energy was taken away from me I really noticed it. So yes, life with a closed-loop insulin delivery system has definitely improved my sleep!


As it happens, my friend Renza at Diabetogenic wrote about improved sleep recently, although she has noticed it in different ways.

Also, that meeting with my endo last week was a very positive experience. My CGM data shows my “time in range” has improved, with dramatically fewer hypos and hyper events, and my average BG has dropped to levels usually seen in people without diabetes. Both my endo and I are very happy with the current state of my diabetes.

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