Having now run a combination of OpenAPS and Loop for a full month, I thought it was about time to publish some data from looping, and if possible, compare it to a period where I had been using a CGM and Pump, but not running a Hybrid Closed Loop. And hasn’t it done well!
At this point, it’s worth making it clear that when using CGM and Pump, my approach to managing my T1D has been very much of the “Sugar Surfing” ethos, which means that I have spent time “glancing” and then managing my glucose levels. In many ways, this is not so far removed from what a Hybrid Closed Loop is doing, only that the “Loop” is you. During the earlier period, I was using Dexcom G4 with xDrip and the 640G, with around three weeks of HAPP interspersed within it.
So let’s take a look at the numbers. Up first are the two Ambulatory Glucose Profile traces. The first is the 31 day period using a Hybrid Closed Loop. The second the 80 odd days using sugar surfing. The “High” line is set at 8.8mmol/l and the “Low” at 3.8mmol/l.
Throughout both these periods, my food intake is fairly variable, with the October looping period being not particularly well managed, with weekends where beer drinking and carb consumption was definitely in play. My typical daily diet included relatively low carb meals for breakfast and lunch, then dinner depends on whether I am at home or out, whether we are having dessert, etc.
Comparing the two, you can see that the loop did a fantastic job of keeping my 25th-75th percentile zone suitably tight. You can also see that my 10th-90th is a little more spikey, and this is principally because as a person using a CGM and then adjusting, I tend to be more aggressive on my adjustments. I’m just glad that the maximum and minimum aren’t being shown on here. The occasional cocktail plays havoc with that.
Comparing the statistical assessment, we see the below tables:
Remarkably, the statistics are really close. The distribution of highs, lows and normal are pretty much identical. The on;y real differences are in the mean/median values, where the loops managed a lower Normal value, and a higher low value. Unfortunately, the high averages were slightly higher, with slightly greater standard deviation. Having said that, I know the reasons for it and am unsurprised.
Overall, these are really great numbers. The key point the numbers get across is that a hybrid closed loop using only insulin is obtaining numbers similar to an intensively controlled sugar surfer.
But that misses the point rather…
The loop is obtaining great numbers without the user’s involvement. It’s doing the sugar surfing for you. And therein lies the difference. Sugar surfing throughout waking hours entails roughly one glance every fifteen minutes. Assuming an 18 hour waking day, that’s 72 glances a day, or 2,160 a month.
That’s also 2,160 moments where you:
- Read the data
- Assess what the data means
- Decide what the appropriate response to the data is
- Act on the data
It might only take 10 seconds, but that becomes six hours a month. And it’s you doing it.
So the loop has removed 2,160 moments a month, outside of eating, where you, as a sugar surfer, casually interact with your diabetes. It’s doing that for you.
And that’s the key benefit of any form of closed loop system. Freedom. You need to spend much less time focussed on trying to get yourself where you want to be. The system does it for you, unemotionally and efficiently, as I mentioned in this post. And here it is, written down in stark numbers.
This is why so many people are looking to move themselves into this new paradigm. To give themselves a little taste of freedom.