Pros & Cons of the Tandem t:slim with Control IQ
Tandem t:slim with Control IQ: “Smahtah” than the average pump
By Gary Scheiner MS, CDCES
I’m a big fan of the new smart car (also pronounced “Smaht Cah”) technologies. What’s not to like? It’s like having another set of eyes watching the road so that you don’t veer into the wrong lane or bump into the car in front of you. You still have to be an attentive driver, but as long as you can put up with a few extra beeps, the “smaht” features make driving a whole lot safer.
Today, we’re in the midst of a smaht technology revolution in diabetes management. Better known as “Hybrid Closed Loop Systems,” or HCLs, they combine an insulin pump, a continuous glucose sensor, and a computer algorithm that adjusts certain aspects of the pump’s insulin delivery automatically. The result is better overall glucose control (particularly more time spent within one’s target range) and less burden on the user to make all the adjustments on their own.
Until recently, we had two HCL options:
- Medtronic’s 670G and a few build-it-yourself system – Loop, Open APS and Android APS. Medtronic’s system can produce pretty decent glucose control, but it comes with a slew of challenges for the user (see review here: https://integrateddiabetes.com/670g-and-me-insights-and-incites-on-medtronics-latest-system/).
- The do-it-yourself systems can produce superior control, but they can be a bear to set up and maintain (see review here: https://integrateddiabetes.com/loop-vs-medtronic-670g/)
Now, we have something new and, some may say, even smahtah: the Tandem t:slim pump with Control IQ technology.
Taking a look at the Tandem t:slim
Tandem’s HCL system features the sleek Tandem t:slim tubed insulin pump with a full-color touch-screen display. CGM data reaches the pump via Bluetooth signals from the Dexcom G6 sensor, which lasts up to 10 days and requires no calibrations. Activating the Control IQ algorithm requires the mere flip of a switch and entry of the user’s weight and average daily insulin requirements. The algorithm predicts where the glucose will be in 30 minutes (based on CGM values and trends) and adjusts the pump’s usual basal delivery based on the predicted value. The system can also administer conservative correction boluses on an hourly basis if the glucose is predicted to be quite high or remains high. It has a preset target of 110 mg/dl.
Extended boluses (but not temporary basal rates) remain an option when Control IQ is running. But the fact is, temp basals are not usually needed since the algorithm makes basal adjustments for the user. If the user knows that their insulin needs will be significantly higher or lower for a certain period of time, they can easily switch to a different “personal profile,” which includes both basal and bolus settings. The system has two optional overrides: An exercise setting (which makes the basal-adjustment algorithm more conservative) and a sleep setting (which makes the basal-adjustment algorithm slightly more aggressive but turns off automated correction boluses).
In pre-market clinical trials, Control IQ achieved glucose management outcomes similar to those of Medtronic in terms of average (mid-100s) and time-in-range (above 70%) with a low frequency of hypoglycemia. However, Tandem’s studies had few restrictions in terms of participation. Our experience (with patients who are well-educated on diabetes self-management) has been that Control IQ produces even better outcomes. Compared to Medtronic, the amount of work required by the user to maintain the system is much, much less. Compared to DIY systems, the setup is much, much easier.
The Tandem pump (along with CGM data) has its own download software (t:connect) which displays sensor and pump data on the same reports, but is a bit clunky to navigate. The reports are clear and simple, but little is offered in the way of computer-generated analysis/insight. The pump can also be downloaded to “midware” programs such as Glooko and Tidepool.
Unique Advantages: Pros
The Pump
The pump is sleek and easy to program, with a display that really pops. The menus are intuitive to navigate. The confirmation steps can be a momentary annoyance, but they greatly enhance the system’s safety.
The Sensor
They say you’re only as good as the people around you. Tandem was very, very smaht in linking with the Dexcom G6. It’s an easy, accurate, dependable sensor that does not require fingerstick calibrations.
- SimplicityAs noted above, Tandem built their HCL system largely around the needs of the typical consumer. Most people do not want to have to do extra work. And with this system, they don’t. Just turn it on and it runs quietly and consistently in the background. There are no added alarms or user interventions required to keep the system running other than having a steady stream of input from the CGM.
- Updatable FeaturesOne of the unique aspects of the Tandem pump & algorithm is its flexible nature. The software can be updated through a simple download. The upgradeable software also means that users don’t have to wait until their pump is out of warranty to benefit from new and improved features.
- Automatic Glucose EntriesDelivering timely, accurate bolus doses is still the responsibility of the user. The Tandem system makes this faster, easier and more dependable by automatically populating the sensor glucose value in the blood sugar entry field whenever boluses are being calculated. One less step and one less chance to accidentally make an incorrect entry.
- CustomizationWhen Control IQ is running, all of the user’s usual basal and bolus settings are applied (except for the target and duration of insulin action – see cons below). The basal part is very important, because having the proper basal settings means that the system spends less time “chasing” rising/falling blood sugars, and can focus on maintaining within a healthy range.
- Correction BolusesThis is unique to the Control IQ algorithm. By administering correction boluses on the user’s behalf when glucose levels are predicted to be (or already are) above 180 mg/dl, the Control IQ algorithm is faster than other HCL systems at fixing high blood sugars. Users still have the option of programming correction boluses on their own – something that is not available in all HCL systems.
- Sleep ModeWhoever thought of this deserves a nice nap. For those who want to keep their blood sugar in a tighter/narrower range, sleep mode works quite nicely. Some users even choose to apply sleep mode around the clock.
- CoverageUnlike Medtronic’s 670G and the DIY systems, Tandem’s Control IQ is covered by Medicare and most private health insurance plans. United Healthcare is a glaring exception (United only covers Medtronic), but that may change as pressure mounts for United to update its policy terms.
Potential Drawbacks: CONS
Lack of Training
Don’t misunderstand. Anyone who is new to using a Tandem pump will receive thorough training by a qualified company representative or certified private trainer. But for those who are updating from an earlier version of a Tandem pump, face-to-face training is replaced by an online tutorial. While this works for most people, it is not ideal for everyone.
- Fixed IOBFor a system that offers flexibility/customization in so many ways, it is surprising that the “duration of insulin action,” which is used to calculate insulin-on-board (IOB), is not something that the user can set. It is fixed at 5 hours, which is longer than most people’s rapid insulin lasts. The result is a slight over-estimate of IOB most of the time.
- Extended Bolus LimitsWhen Control IQ is running, extended bolus can be set – but only for a maximum of two hours. While this works well for most situations, it may not be long enough for those with gastroparesis or when consuming very large/high-fat meals.
- Limited Display InformationThe Tandem display only shows when Control IQ is currently raising/lowering basal insulin or administering a correction bolus. Specifics are not available on the main display, nor is recent history of food, boluses, or automated adjustments (other than suspensions).
- The ClipI realize that this has nothing to do with the hybrid closed loop aspects of the system. But they really screwed this up. The clip is weak, the case is awkward, and the orientation is upside down.
- Exercise ModeAs is the case with other HCL systems, the exercise mode provides “too little too late” for preventing lows with most forms of exercise. If set 1-2 hours prior to planned activity, it can be helpful for reducing carb requirements during a prolonged bout of exercise, but don’t develop a false sense of security. For most traditional forms of exercise, the usual user-initiated adjustments (involving food and/or bolus insulin) are still required.
- TubingSay what you will about tubing. Most users of traditional pumps get used to it fairly quickly. But many still find it inconvenient and unsightly. The change-out procedure has many steps, and air pockets sometimes form. The need to connect/disconnect on a regular basis can also impact glucose control.
Overall, Tandem’s system offers a nice value proposition for users. It is accessible, easy to set up and use, and produces nice results without adding any extra work/burden for the vast majority of users.
For a side-by-side comparison of all available HCL systems (including a cool star-rating for various features), visit the resources section of our website: https://integrateddiabetes.com/what-is-a-hybrid-closed-loop-system/hybrid-closed-loop-comparisons-options/
I really appreciated this write-up! Thank you Gary! I am one of “casualties” of being on Medtronic’s 670G for the past 4 years. I got SO burned-out. It improved as they improved the sensors, but readings were still a good 30-40 points off which is a bad place to make ANY treatment decisions regardless of how good the algorhythm seemed. Furthermore, I was also being overdosed on insulin and gained weight on it. Have you heard of others experiencing that? After getting the Dexcom G6, I have finally begun to feel as if I actually know what I am doing again! (Type 1 for 43 years). How much of a challenge was it to switch from the 670G to the Control IQ? I’m nervous about changing pump companies after being with Medtronic all of these years. Do you anticipate that some of the cons you listed may be remedied by Tandem when they update their software? What is this interesting method of filling up cartridges? I think I am a bit spoiled with the Medtronic pumps regarding set changes.
Hi Tami,
I switched form Medtronic to Tandem, it was no different from any other pump order I’d done really, the biggest difference being that now my supplies don’t come direct from the company (Tandem) they come through a third party distributor, this can be a minor hassle but if you keep on top of your supplies it’s not much different.
The Tandem system works based on our programmed settings, rather than the system’s mysterious calculations, so we are able to tailor in its functioning a LOT more to avoid lows and the excess insulin and weight gain that often comes with hcl start.
The cartridge refill is the one big down side to the Tandem pump. I recommend paying close attention in training, and watching the online tutorial videos to make sure you’re doing it right to avoid having air in your tubing and the accompanying problems there.
No word from Tandem just yet on further software upgrades to control IQ, but Tandem has a decent track record at listening to what customers want and delivering (Certainly more than the other manufacturers) so I’d expect to see some improvements.
Switching form the 670 system to control IQ will proabbly require some retooling of your settings since they tend to get a bit artificially out of whack trying to make Automode (670G) to work well. But we specialize in that area so feel free to give a call and schedule a consult.
I wish the LIES of a “non-stick” Dexcom G6 CGM would stop. I like my Dexcom G6 (overall), but I have to do a finger stick about 30 minutes after a sensor change warmup, because in most cases, I have to calibrate. When I do calibrate, I do another finger stick the next day for a follow up. In most cases I am OK, but from time to time, I have to calibrate again. If I do, I repeat daily, until I am OK. Two finger sticks in ten days is the norm.
Since Jan. 2020, I have had two bad sensors, which initially throws my readings off and would affect the Control-IQ. (No problem in getting the sensors replaced.) With two other different sensors, I have had to make additional calibrations later into the ten days – not the norm, but follow your body ‘s feelings. Ninety eight percent of the time, the Dexcom G6 is almost exact as my glucose meter and clinic lab, but again, watch for the exception.
For a short time now, I am using Basal-IQ (working good) and am looking forward to the Control-IQ, with a close eye on the G6. The Control-IQ will be only as good as the G6 input.
Hi marvin, the “no finger stick” advertising is right up there with “one size fits all” and “individual results may vary” because no two people are going ot have the same experience. many people can use the G6 effectively with only a few finger sticks in a month, others find they need more oversight. We work with our clients to help reduce issues that can lead to reduced accuracy with CGMs as well.
Great post. Wanted to let you know that we hacked my daughter’s clip and it works great. We took an old clip (best clip ever) from J&J Animas Ping, removed the screw to make it smooth, and used 30lbs gorilla double sided tape to attach it to the back of the pump. It’s excellent and has never fallen off!
We love the system, but another con is that exercise mode doesn’t have a schedule, it’s either on or off. And kids forget to turn it off.
PS – email me if you want to see a pic of the hacked clip. Can’t stress enough how great it works.
Thanks for this write-up Gary. Very informative. My t:slim G4 pump just went out of warranty, so I am leaning heavily towards the X2. But I like to read the real-world experiences before diving in.