Tandem Control IQ

Even within a few weeks of starting on Control-IQ by Tandem Diabetes Care, I knew that this new system that helps automate insulin dosing was the right choice and could help me better manage my diabetes.

Even though I have some suggestions for improvement, the high praise continues in the year 2022.

The pop culture analogy that best describes my experience so far is that Control-IQ is like Baby Yoda — it’s cute and photogenic and has gone viral online. Sure, it has some mystical skills but it gets tired easily and can’t yet fully tap into “The Force” to keep me at optimal glucose levels all the time.

Control-IQ has been a wonderful device, but sometimes it leaves me wanting to throw it to the floor. Control-IQ has helped me achieve results between 70 to 180 s/dL more often than not, up from the roughly 34% before.

Control-IQ (or CIQ as some of us fondly call it) is one of the newest “closed loops” or automated insulin delivery (AID) systems, which connect an insulin pump, continuous glucose monitor (CGM), and control algorithm. These pieces create a system that can mimic what a healthy pancreas does, by monitoring glucose levels and delivering insulin as needed.

The Food and Drug Administration (FDA)’s approval of CIQ in December 2019 was big news for the diabetes community. It became one of the most advanced diabetes technology commercially available, aimed at reducing the number of low and high blood sugars one experiences.

CIQ combines the t:slim X2 pump with the t:G6 CGM to help keep blood sugars in range. It works hard to keep you as close to 120 as possible, using a variety of methods.

It is not a silver bullet, but it is focused on helping you do better and thinking less about the ups and downs of diabetes.

Users still have to take insulin bolus doses for meals, because the system doesn’t automatically do that. But the auto-correction function can help reduce high blood sugars more quickly if you miss a meal bolus or miscalculate. This is a huge advantage for most of us whose carb-counting skills are far from perfect, making mealtime insulin doses hit or miss.


  • The Tandem t:slim X2 pump is small and attractive.
  • The pump allows you to enter data.
  • The pump home screen has various time views and data on it.
  • You can view pump and CGM data through the app on your phone.
  • “If you choose, you can enter fingerstick readings if you choose, but the pump and apps don’t require fingerprick tests.”
  • You can program different settings for the rates.
  • The device has two modes of sleep and exercise that you can use to fine- tune your blood sugar levels.
  • Users report improvement in the accuracy of their tests.


  • You have to wear two devices on your skin at the same time.
  • The pump requires charging at least once a week.
  • Some feel that the first generation of Control-IQ has a too high target for theglucose.
  • The system runs on readings from the G6 and if the sensor is malfunctioning, the automated features will be affected.
  • The pump home screen needs to be unlocked for safety reasons.
  • Some people say that dropping the t:slim X2 results in a cracked or shattered screen.
  • The clips for the pump are not designed to stay attached to a beltline.
  • It is expensive, and may be a barrier for some.

The system is cleared for children as young as 6 years old and adults with either type 1 or type 2 diabetes. The basic features of this system are shown here.

Touchscreen and sleek design

The first pump to feature a touchscreen is the Tandem t:slim pump, which feels more modern than most pumps. It feels like a cool piece of tech, rather than just another piece of medical equipment, because of its colorful app interface.

You can also decorate your pump with “skins” to show off your style. The CGM data is displayed directly on the t:slim X2 pump touchscreen with all the typical graphs and displays showing the current glucose level, plus data going back 3 to 24 hours.

Remote upgrading

The system uses the t:slim X2 insulin pump platform that was the first to allow remote product updating from home, so you don’t have to trade in for a new piece of hardware every time some functionality gets upgraded. You just access Tandem’s t:connect customer portal to activate the upgrade.

No routine fingersticks

The system uses the latest G6 model from Dexcom, so it does not need to use additional fingersticks for FDA calibration. If you prefer, you can do backup fingersticks.

Pump charging

You’ll need to charge the t:slim X2 pump using a micro-USB cable provided with the pump. Tandem tech support recommends topping it off each day for 10 to 15 minutes, even though you could likely go several days without charging if necessary.

You can order extra cables to keep at home, in your car, or at work. Many people use their pumps for a short time when they are disconnected for showering or when they change their IV sets.

Auto insulin shutoff and resume

Control-IQ automatically shuts off the delivery of the drug when the CGM predicts that your blood sugar will fall or rise. The system will immediately resume the production of the drug once your blood sugar is back in range.

Auto basal adjusting

Control-IQ can help keep your levels in range, even on the low and high end of the spectrum. The smart algorithm behind this feature was acquired by Tandem Diabetes years ago.

Glucose target ranges

Control-IQ has a variety of target range settings that are different at different times of the day.

  • The regular target range is between 112 to 160 s/dL.
  • If the CGM predicts you will rise above 160 mog/dL in 30 minutes, it will increase your rates.
  • If yourglucose is predicted to go above 180 in the next 30 minutes, it will automatically deliver a correction, but only a small amount of what your pump settings dictate.
  • The Sleep Activity mode allows for a more aggressive range of 120 to 120. You can set specific times overnight or leave it on for the tighter range if you choose.
  • The target of 140 to 160 s/dL can be achieved with an optional exercise mode.

Auto-correction boluses

The t:slim has a built-in wizard that helps you calculate the amount of food you should eat based on your blood sugar correction and your type of food.

Control-IQ system has an auto-correction function that can help reduce high blood sugar quickly. If yourglucose is predicted to go over 180, you will be given a bolus that is about 60 percent of the correction amount.

“This works on top of the self-adjusting rates. Control-IQ doesn’t automatically make the meals’ boluses, but it can help reduce high blood sugars if a meal is missed or calculated wrong.”

Optional sleep and exercise modes

The Sleep Activity mode allows for a more aggressive range of 120 to 120. You can set specific times overnight or leave it on for the tighter range if you choose. The optional Exercise mode allows for a target of 140 to 160 mg/dL.

The first version of Tandem’s t:connect app came out several months after Control-IQ. This app works on iOS and Android smartphones, though only certain phones are compatible.

“The app allows you to see your t:slim X2 pump’s features, including your TIR for the last 24 hours, and you can also see your blood sugars, and even see your IOB. Your data can be shared with up to six people.”

The second version of the t: connect app allowed you to dose your diabetes medication from your phone. It included several other feature updates, including alarm changes and what icons appear on the screen. A new app update and a 30-minute training is required for that update.

Only a few of the devices were compatible as of August 2022. The company is getting them cleared by regulators.

The mobile app update will allow for full pump control from the phone app. That is expected in the year of 2023.

The upgrade process was simple.

  1. I logged into the t:connect portal online. This started a 5-step process confirming my Dexcom G6 use and receipt of my doctor’s prescription.
  2. I was ready to start the training, which took 40 minutes for the first part and 20 minutes for the second part, after all that was confirmed. It provides online traffic school or employee training that many do online.
  3. After completing those modules, I got an authorization code that allowed me to proceed with the update to my t:slim X2 — going from Tandem’s previous Basal-IQ system to the new Control-IQ feature.
  4. “The system made me load a new diabetes device and start a new CGM session. I was still wearing the G6 sensor, so I didn’t lose it. After a brief warm up period, it started generating data on the t:slim X2 screen.”

Important: Once you update from Basal-IQ to Control-IQ, you can’t go back to the earlier version. So for anyone who isn’t sure about updating just yet, think twice before making the switch.

As time went on and new updates or app versions were released, I had to go through periodic online training sessions to confirm these changes. That usually required me to use the Tandem Device Updater tool, a simple process complete with easy-to-understand prompts and instructions.

I need to go through this process with my new phone to make sure it is ready to use with the Tandem technology.

“The system helped me get some impressive results that I hadn’t been able to achieve before. It gave me new information about how much I use ofinsulin throughout the day and helped me figure out how my food and drink choices affect my blood sugar levels.”

I am not a statistics-savvy person, but I am still fascinated by the fact that in my first 2 weeks with Control-IQ, my rates were adjusted 1,794 times, with 98% of those being auto increases or decreases.

The average number of days I delivered a dose was six, with 23% of them being corrections and 11% being extended. I used the calculator for 45% of my daily dose, and the rest was delivered via Control-IQ.

  • The lows are about the same as before.
  • The highs are only 13%, down from 33%.
  • The system automatically corrects to avoid highs overnight, and the lows are predicted ahead of time, which improves sleep.

“Sometimes I get rebound highs that the system can’t handle. I tried out Exercise Mode for the first time while shoveling snow and added a muffin.”

I went high thanks to that muffin and the exercise adrenaline boost but eventually bottomed out from the delayed snow-shoveling effect. And my rescue carbs ended up being too many Girl Scout cookies… no surprise that I ended up in the 300s with CIQ chugging uphill to catch up.

There are no diabetes tech that can deal with those monkey wrench.

Control-IQ helps me to follow my data more closely, and it teaches me about exercise and sleep.

It helped me to stop over-treating when my blood sugar goes low, because the auto-shutoff and the basal adjustments help me recover more quickly.

I find some features helpful.

1. Retention of extended boluses

If you went low during the scheduled bolus, an Extended Bolus was canceled. Control-IQ allows you to continue delivering the rest of the Bolus if you want.

2. Delay of insulin restart

Once the data from the CGM shows that yourglucose levels have started to rise after a low, the system does not immediately resume deliveringinsulin. It takes a moment to assess three of your past four readings to make sure you are rising before it kicks in.

3. Exercise and sleep activity modes

I have learned that you can use the optional activity modes in ways that are not what the manufacturer intended. I am using the Exercise mode to shoot for a higher target range of 140 to 160 s/dL to avoid lows.

If needed, the system will give an auto-correction dose. I have been using Sleep Activity mode for those times when I am not as active as I would like, and I would rather not have an auto-boluses delivery.

Several items jump out at me.

1. Display colors and icons

The use of tiny icons is a problem for me because they are hard to see on the pump.

  • A diamond icon in the top left corner of the screen indicates that the system is turned on.
  • A letter B is in a box at the top right corner.

If the system is decreasing the amount of blood in the system, the orange icon will change to blue, while the blue icon will be used for the insulin drop icon.

I have trouble differentiating the different colors of these icons because I am partially color-blind. I would like to see the icons bigger and more intuitive to reflect a higher or lower rate of activity.

2. Better detail on adjusted basal rates

“To find out whether the system is increasing or decreasing the rate, you have to touch the little B icon in the top screen. It doesn’t tell you how much the rate is different from the pre-programmed rate.”

It would be better to have the programmed rate displayed above or below the adjusted rate, so you can understand how it is adjusting to your needs.

3. Slow reactions require patience

The biggest lesson for me is that Control-IQ doesn’t react to big changes quickly. That, along with the slower action of the Novolog insulin in the pump compared to the inhalable Afrezza insulin I’d been using previously means I have to remind myself to be patient and let Control-IQ do its work before over-reacting and manually delivering more insulin.

4. Dexcom is the weakest link

“I have been a fan of the CGM from Dexcom for a long time. The G6 hasn’t performed well for me. I get a lot of instances when the signal is unreliable.”

I have used G6 according to the guidelines but have never had a 10-day sensor. Only a few of my sensors have lasted the full 10 days. I get a sensor for 6 to 7 days before it malfunction and stops the session. I have to call in each of the early failures to have my sensor replaced.

If other people are having issues with G6 sensors, this could be a big problem for patients to use Control-IQ.

The retail price of the pump is $4,000.

That is very expensive. Health insurance typically covers 80% of that cost, according to Tandem. That is what I found with my insurance plan.

Supply cost

You need to purchase all the supplies separately. The retail price for a single G6 transmitter is $237 and the cost for a box of three 10-day sensors is $349.

“The Tandem t:slim X2 is the receiver that connects to the G6, so you don’t need a separate receiver. If you don’t have insurance, you can order lower priced supplies from the store.”

Product Manual calibrations? Insulin pump tubing? Auto-corrections? Phone control
Tandem Control-IQ no yes yes bolus only
Medtronic Minimed 770G yes yes yes no
Omnipod 5 no no no full phone control

Some people with diabetes have chosen to build closed loop systems using the open source algorithm or the model of the Dexcom CGM. Do-it-yourself systems work almost exactly like the Tandem or Medtronic systems, but they require a lot of trial and error. They are not FDA-approved.

Finally, there is the new Bigfoot Unity automated insulin delivery system that was cleared by the FDA in May 2021. Unlike Tandem Control-IQ its competitors that all use an insulin pump, this new system is designed for users who manage their diabetes with multiple daily injections (MDI therapy). Bigfoot Unity may offer an attractive alternative for those who want the power of a closed loop system without the need to wear a pump device.

Here are answers to some questions we have heard about this new technology.

What if you have ’tight‘ diabetes control already?

Control-IQ has some limited fixed settings, including the 112 target, which is true. If you want to control it tighter, you might want to change the number. I coast between 100 and 150 of the time. It is easy to adjust my settings to push me lower if I want to run tighter.

Does Control-IQ have a set 5-hour insulin duration?

“Yes, it does. Control-IQ doesn’t allow you to change it. The time frame for how long the pump will calculate the IOB is fixed at 5 hours. It is a longer active period than many are used to, but Tandem says they chose this to allow the algorithm to deal with simultaneous calculations for potentially multiple insulin doses. I haven’t experienced any negative impacts from this.”

How does Control-IQ compare to Medtronic’s Minimed 670G?

Wil was a former clinical educator and used both 670G and Control-IQ. He shares a perspective.

Both systems did a good job of controlling blood sugar, but Control-IQ is more robust. When a new sensor was being put in, the Tandem pump fell out of auto-mode. Control-IQ was less of a burden in terms of life interference, and I woke up with an excellent sugar range.

This technology is very advanced. No diabetes tech can make that promise. Improved TIR has made me a fan. Quality of life improvements have made me feel more in tune with theDiabetes Force. Control-IQ has new features that I am excited to see grow as we move forward.