Discussion of Tandem's recently released Basal-IQ function

Does anyone know how the Tandem basal IQ compares to the 670g or what you are using?

It is not uncommon for Animas users to switch to Tandem.
The Medtronic 640g is comparable to the Basal-IQ / PLGS update.
The Medtronic 670g / 690g is comparable to the Control-IQ / HCL update.
(690g obviously not released)
As you undoubtedly are aware, Tandem has the ability to remotely provide updates for the X2 pump.
The Tandem Basal-IQ / PLGS update is FDA approved and scheduled to launch this month (August 2018).
The Tandem Control-IQ / HCL update has a launch goal of Summer 2019.
The Medtronic 640g uses the Medtronic Enlite Sensor.
The Medtronic 670g users the Medtronic Guardian Sensor.
The Tandem Basal-IQ and Control-IQ are (and will) use the Dexcom G6 sensor.

We will download and update our Tandem upon launch. According to Tandem Customer Support, it will not work with our G5. I plan to verify that myself.

In the late September or early October, I plan to upgrade to the G6 at which point we would certainly be making use of the Basal-IQ.


For the non-Tandem users, can you give a little summary of what Basal-IQ is?

Basically it just cuts basal when a BG drops below a certain point according to the Dexcom, is that right?

That is my understanding, but Thomas knows much more than me! :slight_smile:

@Thomas Thank you for all the info! We are on Animas until Sept 2019, so I look forward to the Control-IQ. I didn’t even know about that one!

Yes, but it also resumes insulin delivery automatically when bg rises above the threshold according to Gary Scheiners meeting notes.


Looks like Basal-IQ is a little better than that. It shuts down basal if the bg is projected to cross 80 mg/dL 30 min ahead, based on the current Dex trend, and it resumes basal delivery when conditions reverse. Here is an illustration from Tandem’s basal-IQ site:


Reported to be two conditions either of which can stop insulin delivery (assuming stop of both extended bolus and basal).

  • Projected BG below 80 within 30 minutes
  • BG below 70 now and falling

When BG values begin to rise, insulin delivery is resumed.

User choice whether to be alerted or for this to happen quietly (no alerts)

In terms of the Control-IQ forecast for launch Summer of 2019, this will include automated correction boluses for which the 670g does not offer and for which the 690g is scheduled for a trial with this being a significant feature of the 690g. Info on the 690g is kind of sketchy at this point.


We hope that the Tandem system will be more transparent and flexible, and much less user-hostile than the 670G. And the Tandem system will give correction boluses when needed, not just basal tweaks, so there is hope that it will not lead to the multi-hour highs in the 300s that haunt some users of the 670G. But the 670G is available now, so that’s something.

That is important for those of us prone to alert-induced rage. This consideration of the user’s emotional comfort, not just clinical safety, reflects well on Tandem.


I’m married to one of these folks. LOL


Here is a more detailed description which is a public statement direct from Tandem.

Basal-IQ Technology uses a simple linear regression algorithm that predicts glucose levels 30 minutes ahead based on 3 of the last 4 last consecutive CGM readings. If the glucose level is predicted to be less than 80 mg/dL, or if a CGM reading falls below 70 mg/dL, insulin delivery is suspended. Insulin delivery resumes as soon as sensor glucose values begin to rise. Insulin may be suspended for a minimum of 5 minutes and a maximum of 2 hours within a 2.5-hour rolling window.


… insulin delivery can resume with first upward CGM reading.

Although we would likely use this 24x7 unless we specifically see an issue, the biggest benefit is certainly expected to be nighttime. I plan to get the Tandem Basal-IQ update as soon as it is released (which I believe is Monday) and we get our email (which will be staggered across the X2 population of users to prevent an unmanageable surge on Monday for Customer Service and the download servers).

However I do not expect to switch over to the G6 (from the G5) until the Sept/Oct timeframe so it is unlikely we will be able to immediately make use of the update. Tandem Customer Support specifically told me we would NOT be able to use the update with the G5. No reason not to try it anyhow.

Well - one reason perhaps.

If somebody wanted to keep running their X2 in integrated mode with their G5 would be a reason NOT to apply the Basal-IQ update. According to Tandem Customer Support (as mentioned), the update will prevent the G5 from connecting to the X2. As well, the update is NOT able to be rolled back by the customer.


So thinking about the Basal-IQ as described in conjunction with comments Eric has made in the past and what I just saw my T1 do. (Which was pretty cool.)

Just a little while ago.
At 70 with almost 1 IOB w/ cgm heading down and feeling low.
Obviously carb up.

In the car, poked through our “bag” and found a carb of choice for the moment. (I like to bring variety.)

We quickly discussed and came up with 12 ~ 14 carbs should take care of it. (I mooched a couple pieces - lol)

So I was driving and not paying attention to how much was eaten but then saw a bolus being punched in for 0.75 units. Which is the “pretty cool” part and what I recall @Eric having mentioned about why he might bolus when he is already low. Obviously once the carbs were being consumed, somebody wanted more than strictly required for the low. Which when you get right down to it - is a personal decision. :slight_smile: But then adding the extra 0.75 unit to cover the “extra” carbs. That was awesome to see (out of the corner of my eye).

So anyway. Point as how it relates to my previous post. Sorry. I get wordy.

Assume same situation with Basal-IQ in operation. This clearly would have triggered the suspension of insulin delivery. So what would happen when my T1 went to bolus the 0.75 units?

I assume on Monday that I can read the manual and it might have the answer. If not, if somebody is an earlier adopter than we will be, they may be able to answer. Otherwise, we will find out the answer for ourselves in a few months.

In any event - I thought it was an interesting situation.


It’s nice when the young ones grow and learn the arts!

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Please let us know what the system will do, this is an interesting case.

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I thought it only suspended basal? Curious to hear.

That was my first thought. However the wording from Tandem is quite specific in that it suspends “insulin delivery”. I would be both shocked and horribly disappointed if they were not choosing their wording properly.

In any event. Seeing is believing. Everything is conjecture, rumor or second-hand information until we have it in our hands and see what it all really does.


I found a sneak peek of an early version of the manual. Most of the interesting portion that I wanted to read was missing. Figures. A couple interesting notes were available. The manual clearly was going to be revised but one would assume nothing major would be changed? The launch of the update has just started so maybe the real [final] X2 manual w/ Basal-IQ will be online by tomorrow.

EDIT: I just read the final published manual. I saw no changes in the final manual of significance with regards to what I had posted.

If the Basal-IQ. Technology is on and has suspended insulin delivery during an extended bolus, all remaining bolus insulin will be canceled. If desired, a new bolus must be initiated after insulin delivery has been resumed.

If the Basal-IQ Technology is turned on and has suspended insulin delivery during a normal bolus, all bolus deliveries will continue until completed. A new bolus cannot be started until insulin is resumed.

If you manually stop insulin delivery, you must manually resume insulin delivery. The Basal-IQ Technology does not automatically resume insulin if you decide to stop it manually.

If the Basal-IQ Technology is on and has suspended insulin delivery during a Quick Bolus, all remaining bolus insulin will be delivered

If the Basal-IQ Technology is on and has suspended insulin delivery while a Temp Rate is active, the temp rate timer will remain active. The Temp Rate will be resumed when insulin delivery is resumed as long as the Temp Rate is still active.




I hope it works as the manual is currently written. The operations makes sense and would be helpful.

The actual final manual is on the Tandem website and publicly available as the launch of the Basal-IQ update did happen this morning. I already read through it and saw nothing significantly different in terms of the Basal-IQ operations as compared to the pre-release manual.


That is really great news. Once we get on the G6, we can get much more aggressive with our night-time settings and hopefully lower his A1c with little additional risk.

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