FDA approves Tandem Basal-IQ

Today the FDA approved the Tandem Basal-I update. Looks like we will probably see it this year as promised. Woohoo!


I was just reading about this on the Facebook Tandem Tslim page. There are a lot of angry people because they were told that it was being approved to work with the Dexcom G5. A lot of people had made decisions based on that info, now being stuck with the G5 and new orders of sensors. Eventually I just got confused but count me among the disappointed because no one told me to wait and get the G6. I also have a lot of G5 sensors.


It’s good to see the commercial technology moving forward. Turning off insulin delivery in anticipation of a low is a great technique. The CGM data must, of course, be accurate enough to enable the low glucose suspend.

This note on the linked announcement caught my eye.

Using CGM values, the Basal-IQ feature looks ahead 30 minutes and suspends insulin when glucose is predicted to drop below 80 mg/dL or if glucose is currently below 70 mg/dL and falling.

I wonder if this low threshold is user adjustable.

Although I REALLY hope it is adjustable, I am not going to hold my breath.
I like those numbers for my daily life, but if I am working hard in the yard or exercising, I would love to set a higher number to keep myself safe.


There are also times when going below 80 is useful. If you are pre-bolusing for a huge meal, getting a downward trend and dropping below 80 or 70 before you start eating can help prevent a spike. I do it on purpose for certain foods and meals. Making these things more customizable is ideal.


While I totally agree with dropping before eating things like PIZZA!, I think that a large bolus will send you lower, and it will only suspend your basal.
So, if this were the case, you could basically add your basal to the bolus amount and have the same basic affect.

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Being a long time Medtronic user unfortunately the next time I’m up for pump renewal I will probably look very close at Tandem. It seem closer in line with what I’m looking for.

Dexcom integration-from a lot of user accounts Medtronic CGM still not where it needs be from an accuracy, consistent operation, and sensor life.

Closed Loop - I don’t think I want to use the current Medtronic Closed Loop. Based on some user accounts I think I would struggle with it not being aggressive enough to keep me in the bs range that I want.

Small- seems like Medtronic pumps are getting bigger.

Updateable software -With Tandem you don’t have to wait for new pump to get new features.

I do love the Medtronic supply reorder process. They sent me a text message asking if I need more supplies. I respond “yes” and the order shows up at my door a few days later.

Just some thoughts going through my head.


Very nice write-up on the Basal-IQ update for the Tandem t:slim X2 by @Michael_Hoskins.

Looks like it took a lot of time to put together. Very nice job !!!


I’m sold. Ordering the new X2. Already have the G6…

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We have the X2. Ordering the G6…

Seriously - I was just on the phone with Dexcom today. We did the Basal-IQ update but can’t make use of it yet. Hopefully we get the G6 in a reasonable timeframe.

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I will definitely be doing this.
Just waiting for the VA to get my new G6 ordered. They never actually renewed my last order for G5. So I have been making do with replacing my own batteries.
Which means it will not connect with my X2 for now. (not that it matters for the Basal-IQ part now that it requires the G6.)

Was anyone else under the impression that as part of their international study, this basal feature would include increasing basal rates when it’s algorithm said to? This is a full ~2 years behind MT (can’t say their name without causing my blood pressure to go up). :slight_smile: Hopefully working passed all of MT’s issues and being the first desired 100% closed loop.

No. This Basal-IQ update very specifically was always about suspending the basal - never about increasing it. The original name for this was much more descriptive.
Predictive Low Glucose Suspend (PLGS)

This is the first of two major updates that Tandem has been planning for years. And a major reason we picked the X2. (Maybe a year and a half ago we switched to the Tandem t:slim X2 pump?) The other significant reasons for our choice being Dexcom and remote updates. Which all tie together.

The second major update which is planned for Summer 2019 will include automated increases of basal to address high BG as well as automated bolus. Again for the second update, I like the original name which was Hybrid Closed Loop (HCL) as opposed to the new name of Control-IQ. I don’t think the second update is intended to be a “100% closed loop” hence the name hybrid associated with it originally.

The second update (Control-IQ/HCL) appears to be similar to the combination of what Medtronic currently has with their 670g as well as what is planned for their 690g although the operational methods (by all accounts) are completely different.

Choice is good.


I’ve been trying to find out how TypeZero Basal-IQ actually works. I know WHAT it does but they are tight-lipped about how it does what it does, understandably.

Does anyone know if the algorithm uses IOB to determine if a low is going to happen? Or are they just piggy-packing off of the G6 capability of predicting low 30 minutes beforehand?

From what I read, I see no mention of IOB, and I’m left wondering why would they not use that piece of valuable information?

@Anthony - The Basal-IQ (PLGS) does not use a TypeZero algorithm. This was developed in-house. The TypeZero is used with the next update, the Control-IQ (HCL).

The Basal-IQ (PLGS) will suspend on either of two conditions:

  1. BG currently under 70
  2. BG predicted to be under 80 within 30 minutes

So, regardless of who makes the Basal-IQ (PLGS) algorithm, your question is the second condition listed above.

I vaguely remember reading that the prediction uses a simple linear regression algorithm which would imply it does not take into account carbs eaten nor IOB. But there is some hazy memories and some guesswork in that.

This is all so amazing. I can’t believe this is finally happening…

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We just started running the Basal-IQ actively yesterday.

Obviously not much time under our belt.

First impression. Amazing.

Note: We are running Fiasp in the pump. Fiasp is off-label after consultation, discussion and continued oversight by our Pediatric Endocrinologist. Endo has remote access to all pump and cgm data via Diasend and Clarity. Clarity live (3 hour delay) and Diasend after we manually upload the pump.

So far double “Thumbs Up”.


Excellent news. Congrats.

What happens if an extended bolus is entered, but then the low suspend kicks in? Is the bolus also suspended?

@anon85331563. Correct. (And Thanks. :slight_smile: )

Regular bolus in progress (you know how slow the Tandem is on regular bolus - which actually we like and find works more effective) will continue and fully dose even if the suspend kicks in before the regular bolus has completed.

Extended bolus will be cancelled when the suspend kicks in and will NOT be resumed when the suspend releases.

Basal including temp basal rates are all stopped when suspend kicks in but are resumed (including temp basal at the temp basal rate assuming the timer on the temp basal has not expired) when suspend releases.