Tandem t:slim X2 insulin pump with Basal-IQ
Image from Tandem Diabetes Care

The touchscreen diabetes device by Tandem Diabetes Care is one of the most advanced. The smart software predicts the levels of sugars and adjusts them as needed.

The first version of that technology is known as Basal-IQ, a software feature built into the t:slim X2 insulin pump to help prevent hypoglycemia and keep glucose levels in range.

This received regulatory approval from the Food and Drug Administration (FDA) in June 2018. It’s been available since that summer.

The much-anticipated system connects the touchscreen t:slim X2 pump with the latest Dexcom continuous glucose monitor (CGM) to provide glucose prediction and automatic insulin shutoff when low glucose is predicted.

“It is based on the t:slim X2’s ability to be updated from home. New features can be incorporated without the need for a new pump every time.”

Healthline sums up the features, pros and cons, user experience, and pricing of this partially automated AID system.

(Note: Tandem Diabetes Care has an even more advanced AID system known as Control-IQ, but some users prefer the features of Basal-IQ. Read on to learn more.)

Tandem Basal-IQ is a system that integrates the Tandem t:slim X2 insulin pump with the Dexcom G6 CGM and the proprietary Basal-IQ algorithm designed to help keep blood sugars in range. The system can automatically shut off insulin delivery for limited periods if low blood glucose is predicted.

It does this in two different ways.

  • When you go below 70.
  • Within the next 30 minutes, its algorithm predicts you will go below 80.

When your blood sugar level starts to rise again, Basal-IQ automatically restarts the delivery of the drug. Three of the past four readings were used to cause that auto-shutoff. The main screen displays red swatches to show when and how long Basal-IQ has stopped your delivery.

Users can choose whether they want alerts to sound each time insulin delivery is suspended. This allows you to have Basal-IQ in the background, with fewer alerts and alarms to disrupt your day to day. For some people, this can help address diabetes device fatigue.

Pros of Basal-IQ

  • The t:slim X2 is very user-friendly. It has a color screen that is easy to read.
  • The system connects to the G6 and displays real-time data on the levels of blood sugar.
  • It provides protection from dangerously low glucose by automatically turning off insulin When you go below 70., or when the system predicts you’ll drop below 80 mg/dL in the next half hour.
  • “You can turn off most notifications and alert so it doesn’t work.”
  • It has a mobile app that allows you to view and share data from your healthcare team.


  • It only addresses low levels of sugar.
  • It relies on the Dexcom G6 because of the chance of inaccurate readings or a faulty sensor.
  • The t:slim X2 is a modern design but has a number of drawbacks that can make it hard to use.
  • It can be very expensive even with insurance coverage, because you must buy both the Tandem and the Dexcom supplies.

The system is powered by the t:slim X2 pump. The only color that is available on any pump is the one in the color of the pump.

It allows you to remotely update the pump from home, just like you can with an iOS or Android smartphone.

“This was the first one that used an insufficiencies pump. It means you don’t have to buy a new piece of hardware every time a feature is upgraded.”

The pumps are unique in that they use a color touchscreen. There is a three-button wake-up and confirmation series required for safety reasons.

You need to tap on the buttons to get to the screen. When using the pump, there is usually at least one confirmation message for any task you are trying to accomplish, whether it is giving yourself a meal or a correction of your blood sugar.

The pump display shows a CGM icon and data, because it is integrated with the G6 CGM.

You can wake it up by pressing the silver button on the top of the screen, which will show the full-color status screen for the battery, transmitter, andglucose data.

You can scroll through the trace screens without having to repeat the three-button unlocking sequence, even if you want to view the data for 3 hours.

There are some minor issues that some find annoying when using the Tandem t:slim X2 as a diabetes pump.

  • Possible leakage: The little pig-tail part of said tubing is unique to Tandem. For years, people have complained that the twist-and-connect design leaves open the possibility of leaking insulin or introducing air bubbles into the tubing.
  • Multiple confirmation alerts: To unlock and use the touchscreen, you have to go through a confirmation screen each time. People with larger fingers or difficulty with finger movements might miss their target. Thanks to a “three strikes rule,” where the screen locks if you touch an inactive part of it three times in a row, you may need to start over by unlocking it and hitting all the buttons again.
  • Fixed alarms: Several pump alarms cannot be silenced or turned off, including “empty cartridge.” So, if you have a tendency to take a break before you start a new pump session, this alarm will constantly beep without any option to quiet it.

The CGM that powers Basal-IQ is the Dexcom G6. It’s the latest generation of that company’s device as of mid-2022.

You need to purchase the supplies separately to use Basal-IQ.

The G6 is the leader in the market. It gets high marks for comfort and ease of use.

It is FDA-approved for direct insulin dosing decisions, meaning there’s no need to take a confirmatory finger-stick glucose test before making insulin dosing decisions. It also self-calibrates, but you do still have the ability to manually calibrate it by plugging in a finger-stick result if you want to.

The Dexcom G6 sensor is labeled to last on the body for 10 days. As a Basal-IQ user, if a sensor fails early before the 10-day mark, you can contact either Dexcom or Tandem support to get a replacement sensor.

“Some users have reported that the connection between the t:slim X2 and the G6 transmitter isn’t always reliable. Sometimes lost connections can happen when the insulin pump is on the opposite side of the body.”

Tandem first launched its mobile app in 2020. It allows users to see their insulin pump and CGM data and view many features of the Tandem system they’re using (Basal-IQ or the more advanced Control-IQ).

The app was updated in early 2022. Some people use their phones to dose their blood thinners instead of having to use a pump.

Basal-IQ works with t: connect software to analyze data. You can share your information with your care team. They can log in to your account with your permission and view your data to help with your diabetes management.

What you really want to know is how well this partially automated system works to manage blood sugars.

Clinical study findings are positive.

A 2018 study showed that the predictive capability significantly reduced hypoglycemia without rebound highs for both adults and children with type 1 diabetes.

The research showed that 99% of the study participants finished the study. The competing system had fewer people finish the clinical trial because of accuracy and user concerns.

In a 2019 study, researchers looked at data voluntarily submitted by more than 5,000 Basal-IQ users. They found that most of them reported high levels of satisfaction, trust, and usability. It also helped them sleep better and achieve better diabetes management overall.

Many people in the diabetes community have shared their thoughts about Basal-IQ.

One of those Connecticut mothers is namedSamantha Merwin, whose son participated in the Basal-IQ clinical trials. She said it was a miracle when her son woke up and saw how many times the system had stopped his diabetes care.

Brian Mozisek, an early Basal-IQ adopter, liked how the program helped him prevent low blood sugars during his high levels of activity and exercise.

“It helped him to make his settings more aggressive and to watch for higher blood sugars that Basal-IQ can’t address.”

Basal IQ is ‘mostly crazy wonderful’

I have used the Tandem technology for a long time and it has helped to cushion the blow of lows without eliminating them completely.

I have avoided getting into a situation where I need help because of the auto-suspend feature. I have noticed that with continued use of Basal-IQ, I have more confidence to sleep through the night without fear of hypos.

“This is a big deal for my wife and me because I don’t feel the lows much of the time.”

Wil Dubois, a type 1 in New Mexico, gave a glowing review, describing it as “Crazy wonderful most of the time.”

When he first tried the system, he found that it added a whole new level of diabetes control and integration.

“The system was amazing for keeping his blood sugars in check. He did note that it didn’t always catchcoasting lows, the ones where you’re steadily dipping lower over the course of several hours.”

Complaints about Tandem t:slim X2 technology

Every diabetes device has drawbacks. Some have been flagged by Basal-IQ users.

False lows: The Dexcom G6 — just like any CGM sensor — can generate inaccurate readings at times, such as if you’re sleeping on the sensor and triggering what some folks commonly call a “compression low.” This can result in Basal-IQ falsely thinking it needs to shut off insulin delivery. The sensor reading will readjust to accuracy after you take the pressure off it.

Repeat data entry: You must manually enter CGM sensor glucose values into the pump before delivering any correction boluses for higher blood sugars. On one hand, it makes sense since Basal-IQ only adjusts insulin for lower glucose levels. But it’s a bit of a head-scratcher since the t:slim X2 is connected by Bluetooth to the Dexcom G6 CGM and has full access to that data.

Low dosing lock: If your sugars are low, Basal-IQ has suspended insulin, and you want to eat, you can’t layer on a dose of insulin for the carbs you’re consuming. Yes, you may currently be low or at risk of going low. But if you’re about to eat a banana split, it would be a good idea to deliver some insulin to cover it to prevent a rebound high.

Snooze mode cancellation: If you’re not interested in using Basal-IQ’s predictive capabilities, you can scroll to an option to turn off the auto-shutoff feature for a period of time. But if you had started an extended bolus before activating this snooze mode, Basal-IQ will also cancel any remainder of that extended bolus.

No scheduling profiles: There’s no automatic way to switch between basal (background insulin) profiles. This means if you’ve set up a special weekend profile, you cannot set it to kick in at midnight on Fridays. Rather, you have to remember to activate it manually.

Tandem’s newer and more advanced Control-IQ system can adjust insulin delivery for both low and high glucose levels. It offers a number of other features to improve one’s glucose time in range. That system was FDA-approved in 2020.

“You cannot go from Basal-IQ to Control-IQ if you use the t:slim X2 as your foundation. Regulators don’t allow that.”

“If you update your Basal-IQ pump to the more advanced software, you can’t use the older version.”

There are pros and cons to the systems. Some users have said that they were less happy with Control-IQ than they were before because of the flexibility of Basal-IQ.

Make sure to do your research before deciding on one or another. You can read a full review of Control-IQ here.

Affordability is one of the biggest drawbacks of any type of pump.

You can buy the t:slim X2 in its own, but you need to have a Dexcom CGM and access to the automation to use it.

You must buy the Tandem t:slim X2 and supplies, the Dexcom G6 system, and other items. It can be quite expensive with insurance.

The retail price of the Tandem t:slim X2 pump is $4,000. Some plans will cover 80% of the 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.

Make sure to check the discount programs that the manufacturers offer. You can check with your insurance for coverage specifics.

The manufacturer needs to sell the Tandem t:slim X2 pump.

The supplies of the Dexcom CGM can be purchased through third-party distributors, including Edgepark, and retail pharmacy chains like Walgreens.

The Tandem technology can be started.

  1. If you have diabetes, talk to your endocrinologist or diabetes care team to determine if an injection, pump, or device is best for you.
  2. Check with your insurance to see if you have coverage.
  3. “To begin the process of starting a new system, you should contact Tandem Diabetes Care directly or through your doctor’s office. To get a prescription, you will need to contact your doctor’s office, as well as your insurance company to find out the coverage requirements and pricing that apply. This can take a long time depending on many factors.”
  4. After pricing and prescription aspects are finalized, Tandem will work with you or your supply company to get the needed supplies sent to you.
  5. Once you receive the device, you will work with a company trainer or your diabetes care team to determine appropriate settings to program into the device. They will help you learn the new system by sending you helpful videos and resources.
  6. Diabetes devices like the Tandem t:slim X2 and Basal-IQ may take some time to get used to. Some of the ways you manage diabetes may need to be changed as you use the system. Allow yourself time to learn the system and be patient. Remember to keep any return policy details in mind.

When to contact your doctor

You can always talk with your doctor and diabetes care team about your goals for glucose levels and what diabetes technology tools might work best for you.

But meeting with your diabetes care team and endocrinologist may be especially helpful if you’re experiencing any trends in higher or lower glucose levels, particularly if you experience any hyperglycemia symptoms that might signal diabetic ketoacidosis (DKA).

“People with diabetes and their families aren’t suited for the technology of sInsane pumps and CGM. Make sure to talk with your care team about what works best for you and how technology can help you.”

The Minimed 770G and the Insulet Omnipod 5 systems will be available in the US by mid-2022. Control-IQ was launched by Tandem since Basal-IQ first launched.

Here is a look at the other systems.

Medtronic MiniMed 770G: This device combines a Medtronic insulin pump and Medtronic CGM with a controlling algorithm and apps that allow you to track your glucose levels and see pump data. It addresses both high and low blood sugars, like the Tandem Control-IQ version. One advantage may be that Medtronic is the only company that makes both insulin pumps and a CGM, so you only have to deal with a single manufacturer. The downsides are that Medtronic pumps are more “old school” design with no touchscreen. Many reviewers say their CGM is far less comfortable to wear than the Dexcom.

Omnipod 5: As the only tubeless patch pump available in the United States, this system has been available since early 2022. This is one of the most advanced systems on the market. It includes a customizable target for glucose goals rather than a fixed target like the other systems.

Tandem Control-IQ: This has been available in the United States since 2020. It’s a more advanced system than Basal-IQ because it automatically adjusts insulin for both low and high blood sugars.

Here’s a quick glance at how each device compares based on product information and clinical research.

Basal-IQ Control-IQ MiniMed 770G Omnipod 5
Design horizontal
with color touchscreen
small horizontal pump
with color touchscreen
vertical design,
screen buttons
only tubeless
patch pump in U.S.
CGM connection Dexcom G6
(10-day sensors);
finger-stick calibrations not required
Dexcom G6
(10-day sensors);
finger-stick calibrations not required
MiniMed Guardian 3
(6–7 days);
requires 2–3 finger-stick calibrations per day
Dexcom G6
(10-day sensors);
finger-stick calibrations not required
Warmup 2 hours for CGM data warmup 2 hours for CGM data warmup no CGM data during 2-hour warmup; 48-hour warmup before auto mode starts 2 hours for CGM data warmup, but still in auto mode
Set target 112.5 mg/dL 120 mg/dL customizable
110–150 mg/dL
Suspends insulin yes yes yes yes
Auto corrections no 60% of programmed rate to 110 mg/dL target no yes, but more frequent smaller auto microboluses
Phone app yes, with limited pump control yes, with limited pump control yes, but no pump control uses smartphone app or separate controller
Special modes no exercise +
sleep modes for higher glucose targets, auto-corrections
manual and auto modes activity feature for higher glucose target and reduced basal

There are other ways to automate the delivery ofinsulin.

Smart insulin pen systems: The Bigfoot Unity AID system received FDA clearance in May 2021. This system integrates an insulin pen with a CGM. It provides many of the advantages of a connected system to users who manage their diabetes with multiple daily injections (MDI therapy).

DIY devices: Some tech-savvy people with diabetes have chosen to build their own automated insulin 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, Medtronic, or Omnipod systems, but they do require a lot of setup time and trial and error, and their use is not FDA-approved.

How much does the t:slim X2 insulin pump cost?

Insurance plans cover the cost of the technology.

The retail price of the Tandem t:slim X2 pump is $4,000. Some plans will cover 80% of the cost.

You will need to buy supplies each month. Depending on your needs and insurance coverage, these supplies can be as low as $70 to $400.

You will need to buy the G6 supplies separately with Tandem Basal-IQ. The 10-day sensors and 90-day transmitters may cost $6,000 a year.

What insulin does the t:slim use?

The Tandem t:slim X2 is compatible with most of the rapid-acting brands in the United States.

Some people use both Fiasp and Apidra with their pump, though research is not as clear as to whether that is advised.

How long does the t:slim insulin pump last?

The t:slim X2 is covered by a 4-year warranty. The warranty may be dependent on your insurance company policy.

The life span of the pump can be determined by how active you are. Loaner programs are offered by most insulin pump companies if it is damaged.

How often do you change t:slim insulin pump sites?

Changing the t:slim X2 insulin pump sites is advised by medical professionals. This involves putting a new site on your body, as well as filling a new pump with a new type 1 diabetes drug.

You will need to fill the new plastic tubing with at least 10 units ofinsulin and then fill the cannula with a small amount ofinsulin.

Most people who have tried Basal-IQ say that it is a winner. This system only addresses half of the equation, and it only reacts to low blood sugars.

Some people with diabetes may be hesitant about using a partially automated system like Basal-IQ. They may feel like they have to give up their own control of their regimen.

Many people have found that this is the option they need to protect themselves from dangerously low blood sugar events after learning about Basal-IQ.

For some, the online training modules offered by Tandem may be key to successful use.