The Tandem Control-IQ system is one of a new breed of Automated Insulin Delivery (AID) systems that helps people with diabetes manage their blood sugars at a whole new level.

Specifically, it is a hybrid closed loop system that combines Tandem’s t:slim X2 insulin pump and a Dexcom G6 continuous glucose monitor (CGM) to automatically adjust insulin in response to predicted glucose levels. That means if your blood sugar is rising, the system will increase your insulin, or vice versa: If your blood sugar is dropping, the system will automatically turn off insulin delivery.

The t:slim X2 insulin pump is a small rectangular device that can fit easily into your pants’ pocket. It’s unique in that it has a color touchscreen. Like most traditional insulin pumps, it delivers insulin through a tube that is connected to the body via a small infusion set. The pump can be used on its own, but the Control-IQ technology requires connection with the Dexcom G6 CGM for any of the automation features.

The Dexcom G6 includes a sensor and transmitter in order to work. The transmitter is snapped onto the sensor and sends glucose data to a smartphone or a separate receiver, and in this case, that means it’s sent directly to the insulin pump. Data can be displayed on either the Dexcom G6 app or the Tandem t:connect app.

Read on to learn more about the Tandem Control-IQ system.


  • the Tandem t:slim X2 pump is compact and attractive, with its Apple-esque color touchscreen
  • the pump allows you to enter carbs and insulin correction data
  • CGM data is displayed on the pump home screen, with various time views
  • you can view pump and CGM data through both the Dexcom G6 app and the Tandem t:connect app on compatible iOS and Android smartphones
  • CGM does not require fingerprick tests for calibration, but the pump and apps do allow you to enter fingerstick readings if you choose
  • ability to program a variety of different basal rates and correction settings
  • offers optional “Sleep” and “Exercise” modes to help you fine-tune glucose targets during certain times of day
  • users report excellent accuracy and improvement in glucose time in range (TIR)


  • you have to wear two devices attached to your skin in different spots: the CGM and insulin pump infusion site
  • pump requires charging once or twice per week
  • the first generation of Control-IQ has a fixed glucose target of 110 mg/dL that some feel is too high
  • the system runs on Dexcom G6 readings, so if the CGM sensor or transmitter is not working correctly, the automated features will be impaired
  • there’s a three-button procedure required to unlock the pump home screen (for safety reasons)
  • some report that physical activity or dropping the t:slim X2 results in a cracked or shattered touchscreen
  • the clips for Tandem’s pump are poorly designed and don’t stay attached to a waistband or beltline
  • expensive — cost may be a barrier for some, even with insurance coverage
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Made by Tandem Diabetes Care in San Diego, Control-IQ is one of the new “closed loop” systems that connects an insulin pump, CGM, and a controller algorithm to create a system that can begin to mimic what a healthy pancreas does in automatically keeping glucose levels in check. These early systems are called “hybrid closed loop” because they don’t yet 100 percent automate diabetes management — users still have to make manual adjustments around food and exercise.

The Food and Drug Administration (FDA) cleared this Control-IQ feature in December 2019, making it the second-ever closed loop system available on the market (after Medtronic’s initial 670G system).

It’s widely considered the most advanced diabetes tech available as of mid-2021, and is shown in clinical studies to reduce the number of low and high blood sugars that a user experiences. Its smart algorithm not only auto-adjusts basal (background) insulin rates for both high and low blood sugars, but also allows for automatic corrections for unexpected highs to get the user back in range.

Personally, after being diagnosed over 20 years ago, this system feels like an incredible step forward in terms of diabetes technology for me.

The device’s overall preset blood sugar goal is 110 mg/dL, and it works to keep you safely as close to that number as possible around the clock (unless you turn on the optional “Sleep” or “Exercise” mode with higher targets).

Here is a rundown on the system’s features:

Touchscreen and sleek design. The Tandem t:slim pump is the first to feature a touchscreen, giving it an Apple-esque look that feels more modern than most insulin pumps. Honestly, with its colorful app interface, it feels like a cool piece of tech rather than just another piece of medical equipment. You can also decorate your pump with a variety of “skins” to show off your personal 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’s 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 online to activate the upgrade.

No fingersticks required. Since this system uses Dexcom’s latest G6 CGM model, it does not require additional fingersticks for calibration per the FDA as previous CGM generations did. However, you can still choose to do backup fingersticks if preferred.

Pump charging. The t:slim X2 pump must be charged using a micro-USB cable provided with the pump. Tandem tech support recommends topping it off each day for 10-15 minutes, even though you could likely go a number of days without charging if necessary. You can also order extra cables to keep one at home, in your car, at work, etc. Many PWDs recharge their pumps briefly when it’s disconnected for showering, or every few days when they change infusion sets and the insulin cartridge and tubing.

Auto insulin shutoff and resume. Control-IQ automatically shuts off insulin delivery when the CGM predicts that your glucose level will drop below 80 mg/dL or if your glucose is currently below 70 mg/dL and falling. Instead of automatically stopping delivery for a set period of time, the system immediately resumes insulin once your glucose values are repeatedly back in range and rising again.

Auto basal adjusting. Amazingly, Control-IQ has the ability to auto-adjust basal rates to help keep your levels in range — both on the low and high end of the glucose spectrum. The smart algorithm behind this feature was acquired by Tandem Diabetes years ago from the startup TypeZero Technologies (before Dexcom acquired TypeZero).

Target glucose range. Control-IQ has a fixed target, depending on the time of day:

  • normal target range of 112.5-160 mg/dL
  • more aggressive range of 110-120 mg/dL, through an optional “Sleep Activity” mode where you won’t get any auto-correction boluses during those times
  • an optional “Exercise Activity” mode allows for a target of 140-160 mg/dL

Auto-correction boluses. Like most insulin pumps, the t:slim has a built-in bolus wizard that helps you calculate doses for meals based on your blood sugar correction and insulin-to-carb factors. But on top of that, the Control-IQ system offers an auto-correction function that can help reduce high blood sugars quickly. So, if your glucose is predicted to go over 180 mg/dL, it will trigger a bolus that’s approximately 60 percent of the calculated correction amount with a target of 110 mg/dL. This works on top of the self-adjusting basal rates already in play. Control-IQ doesn’t automatically make boluses doses for meals (users still have to do that) but this auto-correction function can help reduce high blood sugars more quickly if a meal bolus is missed or calculated incorrectly.

Optional sleep and exercise modes. The optional “Sleep Activity” mode allows a more aggressive range of 110–120 mg/dL. This optional setting does not allow any auto-correction boluses while it’s activated, and you can set specific times overnight or just leave it on for the tighter range. The optional “Exercise” mode allows for a target of 140–160 mg/dL.

Mobile app. Tandem’s t:connect app, launched in July 2020, links to the t:slim X2 pump and allows you to see your blood sugar readings, insulin on board, basal rate adjustments, auto-correction boluses, CGM transmitter status (battery life and time started), as well as your time in range (TIR) for the last 24 hours. Your data can also easily be shared with up to 6 users.

Ages 6 and up. In June of 2020, the FDA approved use of Tandem Control-IQ for use in ages 6 and up. This is exciting because the only other hybrid closed loop system available for children is Medtronic’s MiniMed 670G, which is approved for children 7 years and older.

Tandem Control-IQ gets praise across the board in online forums, including at JDRF TypeOneNation. One user there who was originally a skeptic of the product wrote, “I have changed my opinion re: usefulness of CIQ Tech for me… I’m very IMPRESSED with the vast improvement in BG [blood glucose] control afforded me… I am not experiencing the many wild swings in BG which were routine for me. I still have to be involved in managing BG but it is many times easier with IQ Tech.”

After taking Tandem Control-IQ for a trial run, DiabetesMine’s own managing editor Mike Hoskins gave high praise to the system’s “Exercise” and “Sleep Activity” modes. “Control-IQ is teaching me lessons about exercise routines and sleep patterns. And importantly, it is helping me to start stepping back from over-treating when my glucose levels go low — because under normal circumstances, the basal adjustments and auto-shutoff curtail insulin delivery and help me recover more quickly without stuffing my face,” he reported.

Diabetes blogger and advocate Kerri Sparling reported at diaTribe that the auto-correction feature was, for her, “like magic.” When she saw her TIR increase to 80 percent, “I may have teared up a bit,” she wrote. “There was something so cathartic and so liberating about doing less to manage my diabetes in a way that was clearly better.”

Similarly, in a video review of the system, San Diego endocrinologist Dr. Jeremy Pettus, who lives with type 1 diabetes himself, said, “It’s common for me to be in range 80 percent or more each day. I feel more comfortable talking about these things and my diabetes because I have a device that’s helping me do it.”

Personally, I too (and everyone I know who is on the system) have loved using Control-IQ. I used the Medtronic 670G before switching to Tandem and was often frustrated by all the alarms, and the fact that the Medtronic CGM was always 40–60 points off, compared to my fingerstick meter readings. And I could never manage to stay in that device’s “auto mode,” because its settings kept kicking me into “manual mode” for a variety of pre-programmed reasons. In fact, my A1C drastically increased while using the Medtronic 670G system because it forced me to always be hands-on and always be thinking about my diabetes, and I felt more burned out on diabetes than I had ever been.

My experience with Control-IQ changed all that. I do have to remind you, however, that the Control-IQ does still require some work. You still have to manually input your carbs and bolus for high blood sugars. Overall, the system isn’t entirely hands-free but it helps you to stay in range more often.

Additionally, since switching to Control-IQ, my A1C has drastically improved, and I have stayed under 7.0% since starting on the system. I have noticed that the Dexcom CGM is extremely accurate, it is always within 5–15 units of my blood sugar when I use a fingerstick meter.

A friend who also lives with type 1 diabetes raved about her experience with Control-IQ, too. She was also frustrated with the Medtronic 670G constantly kicking her out of auto mode. She said, “When I started on Control-IQ though, it was like night and day. It’s easy to use, I have better control over my diabetes, and I don’t have any problems with it.”

Be aware that you will need a doctor’s prescription to purchase both components of the Tandem Control-IQ system. The insulin pump and CGM are sold separately, and once you have both, you simply turn on the Control-IQ feature on the pump to activate it. There are lots of YouTube videos available to walk you through this.

The Tandem pump needs to be purchased directly from the manufacturer, but the Dexcom CGM and its supplies can be purchased through third-party distributors like Edgepark or at many retail pharmacies across the United States, including CVS, Rite Aid, and Walgreens.

Tandem Control-IQ pricing details

Without insurance, this system is far from cheap. The Tandem t:slim pump alone has a retail price tag of $4,000, but with private insurance some plans will cover almost 80 percent of this cost.

For the Dexcom G6 CGM, when you factor in the 10-day sensors and the 90-day transmitters, our estimate of the annual cost of use is $6,000 per year, or $500 a month.

Fortunately, the Dexcom CGM is covered by a large array of private insurers in the United States. As of fall 2020, Medicare does cover the Dexcom G6 as well. But benefits vary greatly, so you’ll need to check on the details of your plan. If you don’t go through insurance, you can check out Costco’s lower-priced CGM supplies for order at cash price for those who qualify.

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Unlike other insulin pumps, Tandem offers free software updates for existing in-warranty t:slim X2 pump users in the United States. Once you purchase the pump, you can update it through the Tandem Device Updater by plugging the pump into your computer using a micro-USB cable.

During pre-market clinical trials, Tandem Control-IQ kept study participants above 70 percent TIR with a low frequency of hypoglycemia (dangerous low blood sugars). These outcomes are similar to those of the Medtronic 670G system in terms of average blood sugars and TIR.

In terms of the CGM itself, the standard measurement of CGM performance is known as the mean absolute relative difference (MARD). With this measure, the lower the number, the better the accuracy. Clinical data for the Dexcom G6 shows it has a MARD of 9 percent with sustained accuracy over the time a sensor is worn. That puts it ahead of all its direct competitors.

I personally have found this device to be extremely accurate. My Dexcom G6 is always within 5–15 points of my readings on a fingerstick glucose monitor. Additionally, my Tandem t:slim insulin pump has never once over-corrected or stopped delivering insulin to create any dangerous low or high blood sugars.

Medtronic is the only other company that currently offers a commercial hybrid closed loop system in the United States.

Tandem Control-IQ is similar to Medtronic’s newest MiniMed 770G (upgrade from the 670G) in that both use an insulin pump and a separate CGM, plus a controller algorithm to regulate blood sugars, and they both feature apps that allow you to track your glucose levels. But the MiniMed system is notably more expensive than Control-IQ, which at full retail price is nearly $8,000.

Also, Medtronic users regularly complain about the need to calibrate regularly with fingerstick glucose tests, incessant alarms, and constantly being kicked out of “auto mode” into manual (non-closed loop) mode.

Tandem Control-IQ, on the other hand, does not require any manual blood sugar calibrations, is always in closed loop mode unless manually turned off, and the alarms are easy to clear and only go off once.

Some people with diabetes have chosen to build their own closed loop systems using the Dexcom CGM, certain insulin pump models, and an open source algorithm (either OpenAPS or Loop). Once set up, these DIY setups work almost exactly like the Tandem or Medtronic systems, but they do require a lot of time, trial and error, and their use is not FDA approved.

Finally, there is the new Bigfoot Unity automated insulin delivery system that was just 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). Once Bigfoot Unity is fully launched, it could offer an attractive alternative for those who want the power of a closed loop system without the need to wear a pump device.

Tandem Control-IQ is the most advanced commercial hybrid closed loop (or AID) system currently available in the United States. It has performed well in clinical studies and so far, gotten a lot of praise among users — especially the automatic insulin corrections that offset highs and lows.

Personally, I find Tandem Control-IQ easy to use, and it helped me lower my A1C. This allows me to think less about my diabetes, while at the same time getting better outcomes! This device and supplies are expensive, however, which may limit access for many people.