Tandem Basal-IQ in Action!


As many of you know, way too many of our nights look like the following picture due to teenage hormones. It is unpredictable though, which has prevented us from being more aggressive. By unpredictable I mean that 3/5 nights look like the below picture, but the other two will be flat lines and we haven’t been able to identify a trigger (other than waking up at 2 am) that would let us enable a more aggressive night protocol. As you can see in the picture below, my son got up at 2 am, treated and went back to bed, but he was really insulin resistant and some nights he gets a second dose of hormones late, which lead to too many nights/days that look like this.

Over the weekend we upgraded my son’s pump with the Basal-IQ algorithm and started using the G6, since we now have a system in place that can shut off and resume the insulin automatically (with minimal alarms if you choose woohoo) we have been cranking his basal at night to be much more aggressive. So, imagine how good I felt when I woke up this morning and saw this:


As you can see in the final picture, the Basal IQ algorithm predicted he was going low, shut off his basal for a time, when he actually went low, it shut it off again, and then he flat lined for the rest of the night until a slight rise just before waking up. If this keeps up we are going to be really happy. Just so I am clear, he didn’t wake up for that low, and didn’t treat, it was all the system working to shut off and restart his insulin that allowed that to happen.


Not having my son wake up at 2 am every night to treat highs - Priceless!


Wow, that is great! It looks like it treated perfectly! There was no eating involved at all? I so want a system like that!!! Interrupted sleep due to diabetes is a major issue for me.

I wonder how it would deal with CGM inaccuracies, though? Last night my Dexcom alarmed for about four hours saying I was LOW. I suspended my pump for an hour, still said I was low so I ate glucose tablets, still said I was low after an hour so I suspended my pump for two hours, and when it still said I was low, I stopped the sensor. This morning I woke up at 12.7 mmol/L so it’s hard to tell if I was actually low or not. But I’d think something like that would really mess up a pump. Does it have a maximum suspend time?


There was no eating at all.

For us the G5 acted as you describe many times, but the G6 appears better, and the G6 to Pump connection has been rock solid, which is really different than the G5 to pump connection.

If the G6’s stay accurate for us, all is good, if not, well then this won’t work very well. We are keeping our fingers crossed!


Yes the maximum suspend time is 2 hours (within a 2.5 hour window), then it restarts insulin.


It’s really interesting, I’ve been hearing great things about the Basal-IQ – but the description of what it does isn’t that different from the Medtronic “Suspend on low”— they both predict lows, shut off basal to preempt them, and then turn on when needed right?

Or can someone chime in with how it’s different? Because I’ve been hearing TONS of great feedback about this whereas crickets for the Medtronic version.


Yes, it works similarly to the outside the US algorithm in the 640 which included suspend on low AND suspend before low. They incorporated this in the US version of the 670 system. But since the 670 offers auto mode, I haven’t heard about too many people working with the suspend on/before low algorithms because they are spending so much time with the Auto mode system.

Also, the Medtronic sensor doesn’t appear to work as reliably as the G6 system, so there is that as well.

But prior to the 670 in the US, Medtronic only had the suspend on Low rather than the far more helpful suspend on predicted low. As you can see in my example, my son used both of those algorithms last night to good effect.


@Chris, this is really outstanding. I have heard the same thing exactly from another father of a teenager. I am wildly optimistic about the potential of this technology. If it holds true, this is exactly what we all needed to see when our kids go to college.


Yes, I agree completely. It will absolutely buy them a little time (2 hours) to wake up in the morning with a very healthy safety margin. This was a primary driver for me and I know @Thomas to purchase this pump. Next year I think we are looking at full Auto mode which will be nice, but it was this algorithm that I was most interested in.


This is what I was waiting for. This is the reason we chose this pump a year and a half ago. The Basal-IQ (PLGS) update has significantly exceeded my expectations.

That does not happen very often.

@Chris - Wait until you get a bit more time then run some Dexcom Clarity reports and compare the current data to previous data. We have only a slight bit more time on this then you but enough to already show huge difference in the Clarity reports which back up what we see and how we feel about this.

EDIT: And all with zero fingersticks.


I am watching the cgm graph right now. (As I work.)
Just bounced off 49. No carbs. No manual temp basal.
Probably went down that low in the first place because I got frustrated over a mild high that was persistent and did a 3 unit syringe on it which was perhaps a bit more than required. Although. It did get rid of the high.

The upward movement is already decelerating. Looks like it will most likely level out in the low 70’s.

One item not mentioned above is there is no minimum duration for the basal to be suspended. Other than obviously the five minute polling interval to get a new cgm data point. The first cgm data point (after Basal-IQ causes the basal to be suspended) that shows an increase in BG will cause the basal to resume.

So in this case, the basal resumed when the cgm reported the BG of 50 (where the previous cgm data point was the BG of 49).


Thanks for the report. 2019 will be my move from Medtronic to Tandem.


@Jattzl and I were just talking about this the other night. I pretty much dislike the suspend feature on my 670G. I believe there are two main problems that probably affect a number of people. The first one is the sensor lag. That lag can turn an effective treatment into an inappropriate one. I hear this over and over in my group. It’s difficult to find the right setting to enable the suspend to be more helpful than harmful. It’s a regular occurrence for myself that I’m not being suspended until I’ve already turned around. I use the Suspend ON low as a safety net rather than attempting to use the feature for preventative measures.

I tried to use the suspend BEFORE low setting for some time and found it had a regular negative effect on my blood sugar. This brings me to the second problem: the 30 minute and 2 hour SET times. Jattzl and I were talking about the difference. Hers is far more flexible, allowing for quick suspensions almost the way the 670G is able to withhold small pockets of insulin in Auto Mode. These very small windows, coupled with a strong sensor, make for an appropriately timed intermittent cessation of insulin, the equivalent, in my mind, of having 3 or 4 carbs here and there to help oneself stay afloat. Medtronic is rigid with the suspension, locking you in for 30 minutes at first, and then, if it is not satisfied there’s been resolution, shutting it all down for another 2 hours. There is nothing in between. The only option the user ha is to end the suspension voluntarily, but you have to KNOW you’ve been suspended (and it’s a quiet little bugger when it wants to be), and you are actually penalized somewhat for choosing to do so. Once a suspend has completed a two hour window on its own, it knocks out your suspend feature for up to 30 minutes. IF you override it and end it early, it makes the suspend unavailable for UP TO 4 HOURS. That’s most of my night. So if I happen to disagree with the first one because I know I’ve treated already and don’t need the suspend, I’m basically without a suspend for the better part of the night. I disagree with my suspends so often, I have finally stopped turning them on.

The Suspend Before Low feature should be the good one. It does work better for some than others, and not all will experience my difficulties. But if you are someone who experiences that lag, the fact that it locks you into 2 hours of it is a tough combination. It has the ability then to preemptively suspend you, but then as a result of not realizing you’ve turned in time to prove resolution before the 30 minute limit, it locks you in for the full 2 hours. This can feel like the equivalent of finding your infusion set has been pulled out.

I have no idea if someone already answered this, or if this even made sense. We talk about suspends a lot over in my other group, and they are an interesting beast.


wow, this sounds so poorly designed. I really wonder what on Earth they were thinking? i have no doubt that many intelligent and thoughtful engineers work at Medtronic, but this seems so obviously doomed to, if not fail, at least be pretty useless most of the time.


I am so excited for you and your son @Chris!!! I was really looking forward to hearing about your experience since I posted the pics of my IQ graphs! I am thrilled to hear your success! It is very exciting. As @Nickyghaleb said I posted about it on her group and tried to explain the difference but as usual Nicky did an amazing job of summarizing the 670s suspension system. We both had the same experience with it. I was really anxious to use the IQ having used the 670 in the past so I could have a good comparison. It’s the combination of the incredible algorithm, sensor accuracy, much narrower lag time. For me having worn the Dexcom and Guardians at the same time when I switched back to Dexcom it was clear that one of the many reasons for Dexcom’s accuracy over the Medtronic was the combination of sensor accuracy AND the shorter lag time. Without all three working together suspension before low is a useless tool and compunds the struggle for BG control. All the while on the 670 being forced to jump through ridiculous hoops while it “learned” you to get the results it promised compared Basal IQ downloading a program and with no calibration begins working as soon as you turn it on!


We’re gonna get you a shirt. :grin: Because you say you don’t want to sound like a walking advertisement, buuuut… :grin:

I’m very jealous of your little, petite suspend lines there. I’m not gonna lie. :neutral_face:


It is baffling. But worse to me is what we as the users were put through struggling for some kind of success. Even the smallest relief from the 24/7 work of living with this disease and instead having what was suppose to give us that totally consumed my life like never before in my 49 years of living with T1D.


I know. :face_with_hand_over_mouth::woman_facepalming:t3:That’s why I only chime in when I’m mentioned and the retreat so as not to be redundant. It’s always a good feeling to hear others experiences similar to mine. I am so happy to hear @Chris!! And it comes from a place to total relief and gratitude to have something that works so well for me. As always - qualified with everyone it different and will find different ways. As long as they can find it is all that matters.




If I didn’t love it, I wouldn’t summon you so often. :hugs: I want to feel that excited about my device. It inspires me to see you go from diabetes darkness to diabetes light. :two_hearts: I’m going to make you a shirt, and then when we meet someday, you can wear it and I can wear my “I Survived Auto Mode 2018” one… and we can laugh and laugh and laugh.


I’ll wear it proudly!! Key word being “survived”! It was a close one :rofl: