Tandem CIQ insulin duration

I have not seen this discussed before; if I have missed it I hope someone can redirect me. I believe CIQ is supposed to assume insulin is active for 5 hours on the Tandem Tslim pump. But it seems to me that IOB is zero at 4 hours on my pump and I continue to see a BG drop even with a zero IOB reading. This sometimes results in lows. Insulin duration cannot be adjusted when using CIQ. How do you address this?

I actually have the same problem. Everyone cried about the five hour thing when Control-Iq was first introduced, when they were used to 2-3.5ish before, but it’s since gone quiet since for the most part people have figured out that the 5 hours is pretty good. Control-Iq’s new algorithms include the painfully long tail where insulin action is tapering off. For that last hour or so, the insulin remaining is approaching zero. Often it’s a value too small to display. It’s also a net value, only showing the amount of insulin in surplus of your basal rate. So if it has withheld any basal insulin, the IOB is reduced by that amount. It’s highly complicated, hehe why there’s no countdown timer, because these living systems are always adjusting insulin.

But like you, I also wish I could set the DIA longer. I seem to process a little slower than most. I was already using 4.5 hours on the old algorithm before Control-IQ.

The good news is that Tandem is working on bringing us more customization options. There’s already a revision pending with the FDA, but this one coming very soon is only small changes. (I suspect lowering the target glucose to 100, since this is the only selling point Medtronic’s 780 has over Tandem and it’s a bone if contention, but I could be wrong.) They haven’t specified what exactly, just that they’re small changes. The big customization ones, which I assume DIA will fall under, are coming in the next update. That one won’t be filed until the current one gets approved, though. They keep saying that the first filings are prerequisites for the next filings. So it’s all a waiting game.

In the meantime, I would suggest lowering your correction factor a bit to a smaller number. That’s the setting that controls how much insulin the pump withholds to prevent a low. It still works, even when it doesn’t think you have iob, since it’s based on Dexcom predictions. A CF that’s too high pretty much cripples the system, but the lower setting will better prevent the low. You want to make very small changes, though, because a CF that’s too low is it’s own bag of problems and a crazy roller coaster of extremes. With a good CF, I almost never drop below 65 after a meal and seldom actually have to treat for a low, unless I completely botch a bolus.


Thanks for your response. I will try changing the correction factor. I do hope they allow more customization in the future and would really like to see a target of 100. While only a small change, I know it should help me lower my average BG a little.

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