Tandem Basal-IQ Article - Real World Retrospective Analysis


FYI: Original name of Basal-IQ was Predictive Low Glucose Suspend or PLGS for short.

Methods: Retrospective analysis of Tandem Basal-IQ users who uploaded at least 21 days of PLGS usage data between August 31, 2018, and March 14, 2019 ( N = 8132). [clip]

Conclusions: Introduction of PLGS resulted in effective and sustained prevention of hypoglycemia without a significant increase in mean blood glucose and may be considered for people with type 1 diabetes at risk for hypoglycemia.


I won’t say I’ve read it all yet, but I think I read enough to feel like it explains what I feel the difference is between the 670G and t:slim. Both successfully minimize the number of episodes (or decrease severity) of the hypoglycemia I experience. T:slim does that without sacrificing my numbers on the other end. I know not everyone will experience that sacrifice, but for the people who do, it’s enormous.

Oh! I’ve had someone in my group say they were offered a t:slim with Control-IQ… just the other day, implying that the pump they will receive any day now will come with Control-IQ installed. I wonder if maybe she has misunderstood something… It’s not an option for anyone as of today, is it?


Probably a misunderstanding.

I think it would technically be illegal for Tandem to offer (ie - market) that prior to it being approved by the FDA.

Right now the only people legally allowed to run Control-IQ are the 168 people from the clinical trial. Tandem created a new extended trial for them specifically so they could continue to run Control-IQ until it is actually approved and released.


I’m more concerned about their control-iq now. They did the same thing Medtronic did with the 670g. The hard target of 112.5 is much better than Medtronic’s 130, why put the soft 160 threshold in there too. One micro correction bolus of 40% of the actual amount needed has me worried as well.


I agree, @Jason99. I think for people who have experienced the downside of the conservative algorithm on the 670G, it can be a little hard to feel excited about anything that’s in the same ballpark, but…there are a few differences that maybe (:crossed_fingers:) will have some real impact. One such difference is the sensor at the core. The G6 is a much stronger sensor for most, really cutting down the lag time. So much of what people complained about on the 670G was how long it took for it to resume insulin—much of which was a result of that lag. I feel like just having a stronger sensor may have cut the amount of time I was suspended in half. Might not fix everything, but that would be significant. Another difference is that Auto Mode does not make any attempt to adhere to your programmed basal rates from Manual Mode. Control-IQ supposedly will deliver your basal rate until you’ve established a need for an adjustment. Now maybe that will look way better on paper than it will in experience, but at least it’s a difference. And a major one. On paper. :woman_shrugging: Mix in an hourly correction bolus, conservative as that may be, and who knows?

I genuinely hope they can swing it so we can have the option to choose which setting we want to use—just like the 670G user can choose between modes. That has turned out to be a lifesaver for the 670, and it would benefit t:slim as well. It makes the pump fully customizable… allowing the user to use each settings for its strengths. I think Control-IQ will not be perfect but will be a big improvement over Auto Mode. I’d love to check it out… but I’m just not sure I’d be willing to ditch Basal-IQ in order to do so.

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The 670 was programmed to suspend insulin delivery for 30 minutes, and the X2 can start delivery again in 5 minutes. I don’t have an issue with either one really.

I just read the data Tandem submitted to the FDA. The control-iq group was in range 70% of the time compared to 55% of the non control-iq group. These numbers are very disappointing for me. I would have expected a lot higher time in range with control-iq. I’m 70% in range all the time without even trying and I have the worst diet you can imagine. My range is 80-150. Most weeks my clarity has me at 85% in range. This group of people in this trial don’t impress me in the least. Tandem should be ashamed this trials group could only manage 70% time in range.

Why is the bolus correction only 40% of the total Insulin needed? This was my complaint with the 670, that until you get to the soft target of 160(Tandem) or 180(Medtronic) the pump doesn’t aggressively attack the high BG, this is especially true with the 670.

I’ve heard from my friend at Tandem that basal-iq and control-iq will both be selectable options with the new update. I love the way basal-iq works, I’ll most likely stick with that.


On paper, sure. It doesn’t always translate so easily though. But this is Manual Mode anyway, and I thought you were talking about what Control-IQ might do compared to what Auto Mode does?

Okay—I think you have to compare that to time in range in Auto Mode, not to what you’re doing with Basal-IQ. There is still an enormous amount of user control with Basal-IQ just as there is with Manual Mode, so I don’t think it’s crazy that people might celebrate a higher TIR with those. Ultimately, the hope is that one of these algorithms can boast the same great success…without the user having to oversee it all. I think it’s a tall task.

I love the upper end of your range and laughed at your on the worst diet you can imagine. And I don’t care to argue with you on your points. Having struggled with Auto Mode the way I did (and Manual Mode with its very hopeful but not very accurate 30 minute suspend), no one is more skeptical of what Control-IQ is claiming to be able to do, but, having observed and logged the heck out of what I saw on the 670G, I am mentioning some interesting differences. I also love Basal-IQ so I’m not pressed to have Control-IQ be the next best thing to a cure, but there are things that leave me a little intrigued… and maybe rooting for them a little. They’re starting off with some pretty humble claims, which really is in stark contrast to Medtronic… I appreciate that quite a bit. I also hope their 70% in range is true for almost everyone and not more promises of magic that leave many in the dirt… :neutral_face:

If you haven’t worn the 670G, just keep in mind it really does look amazing on paper. It just didn’t translate. This might not either, but they’ve honed in on a couple of key areas. And I still won’t give up my Basal-IQ. :grin:

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Tandem told me it should be available this November :slight_smile:

Yes. Tandem is publicly stating they expect to receive FDA approval and for the launch to be Q4.

They are allowed statements such as that however they are not allowed to actually market prior to approval.

I think the FDA approval is likely in October.

I do agree with the point both @Jason99 and @Nickyghaleb make above. Certainly the comparisons to the existing Basal-IQ algorithm and the 670g auto algorithm are valid which I expect lots of people to also be doing.

Hopefully Tandem will launch the Control-IQ update while also retaining the Basal-IQ and allowing the user to switch back and forth between the algorithms. The CEO has publicly stated this is what he WANTS and we have heard from Tandem Sales Reps that this is how it will work. However there is not yet a public statement from the company (that I know of) which definitately states that this is how it will be. And perhaps that is too much for them to say prior to FDA approval. Perhaps exactly how the FDA approves will influence that.

But certainly I want to retain the Basal-IQ algorithm. I want to give the Control-IQ algorithm a try but I do think it is quite possible that we will find we do better sticking with the Basal-IQ.

Being able to choose which algorithm works better for you would really be ideal.

Certainly hope that is how it is released !!!

Exactly how I feel (aside from the 670 which we never tried - lol)


The Basal IQ algorithm is amazing. While it does not stop all hypos it sure does reduce the frequency and improves the quality of sleep. I hope Control IQ is just as good.

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