Tandem Mobi: Should You Upgrade From The t:slim x2?

The Tandem Mobi is one of the newest sensor-augmented insulin pumps (SAPs) – a subset of automated insulin delivery (AID) devices that became available in late 2023. While more accessible in the U.S., the Tandem Mobi will soon be available for purchase across the globe. 

But is this new insulin pump a step up from the latest t:slim x2, and should you make the upgrade when you get the chance? Let’s look at the new pump’s features, cost, usability and the so far, limited, user experience.


The Tandem Mobi is the first of a three-part move towards a tubeless patch pump. It uses a much shorter piece of tubing than other tubed insulin pumps, including its predecessor t:slim x2. 

The t:slim X2 insulin pump operates as a conventional pump or with advanced SAP, AID or (with a CGM) ACE technology. 

The Mobi does all of that but in a smaller package. In fact, it’s the smallest automated insulin delivery device on the current market. The reason this insulin pump is so small is the absence of a screen. That’s because the pump is completely managed via a compatible smartphone app – and phone options are limited. Only an iOS app is (currently) available. 

The Tandem Mobi is a little ahead of the pumps like the Omnipod 5 with CGM integration as it already integrates with the FreeStyle Libre 2 for all countries. Within a couple of months, it will have Dexcom G7 integration and, shortly after, Libre 3 should be added to that list.

The system features the same Control-IQ technology of the t:slim X2- Control-IQ predicts and helps prevent high and low blood sugar by suspending delivery during actual and predicted lows. When the pump is used with the pump’s Basal-IQ technology, it automatically suspends insulin delivery based on current (<70 mg/dL) or predicted (<80 mg/dL within 30 minutes) readings. It also delivers correction boluses for up to an hour to help prevent blood sugar highs.

Tandem provides a simple printable guide to show how the basal rate is set for the Mobi. You can use different named profiles (sport, work, vacation and so on) set to specific times to adjust the amount of basal insulin the Mobi administers. And if you don’t have your smartphone on hand, don’t worry. There might not be a screen, but there’s a physical button on the pump.

The Tandem Mobi received FDA clearance in July 2023 for PWD aged 6 and up. 

Price & Monthly Cost

I’ve had to search forums to find Tandem Mobi prices. One user reported the price of a purchased pump before insurance coverage as $7995. 

Insulin cartridges can be used for 48 hours (Humalog) or 72 hours (Novolog). There don’t seem to be any prices online, but the price for 10 x 3ml Tandem t:slim cartridges is about $50. Tandem Mobi prices shouldn’t be very different. 

The infusion sets are also not yet advertised online. These need to be changed every 2 to 3 days. A pack of 10 (let’s say 30 days) costs around $110.

The approximate total yearly cost with pump, infusion sets and cartridges would therefore be $9915 ($825 a month).

Anyone in the U.S. who bought a new t:slim X2 between July 1 and December 31, 2023 could be eligible for the Tandem Choice Program. This allows users to switch to the Tandem Mobi for $199.

Install Gluroo from Apple App Store
Install Gluroo from Google Play Store

Usability & Comfort

The Tandem Mobi can fit in a small pocket, clip to clothing or be stuck to the body. 

The tubed catheter is unobtrusive. With a short 5-inch (12.7 cm) piece of tubing, the pump is more comfortable and less likely to be dislodged than tubed pumps with longer lengths like the t:slim x2.

It’s small because it doesn’t have a built-in screen (although there are physical buttons). There’s also no need for a controller as the system is completely controlled via an iPhone (not Android) app.

User Experience

Due to its recent development, there’s very little user feedback available for the Tandem Modi. One Facebook user tells us the iPhone app is very different from T:connect and confirms you can bolus directly from the pump in the same way the “quick bolus” feature of the T:slim works.

Another insulin pump user voices several concerns worth thinking about when considering the Mobi. These include the smaller size – meaning a smaller battery and smaller Bluetooth antenna (with a greater risk of radio-frequency interference), and the fact that a broken iPhone means no more insulin pump until the phone is fixed. 

Tandem Mobi vs t:slim x2

Tandem Mobit:slim x2
Pump dimensions (inches)Approx 1.49 x 1.8 x 0.5Approx. 3.13 x 2 x 0.6
Weight (ounces)3.6 oz with battery and full reservoir3.95 oz with battery and full reservoir
Water resistanceUp to 8 feet for 120 minUp to 3 feet for 30 min
Tubing length5 inches23, 32, and 43 inches
Minimum age66
Data management softwareControl-IQ Control-IQ 
Insulin typeU-100 insulin typesU-100 insulin types
Reservoir size (units)200300
Bolus range0.05 to 250.05 to 25
Bolus increments (units)0.010.01
Basal range (units/hour)0.1 – 150.2 – 15
CompatibilityDexcom G6
Freestyle Libre 2
(Dexcom G7 and Libre 3 planned)
Dexcom G6
Freestyle Libre 2
Dexcom G7
Pairs with:iOS smartphone (controller) iOS and Android via t:connect
Data sharing with familyNo (third-party app required)Yes, share with up to 10 people
WarrantyPump only: 4 yearsPump only: 4 years
Average monthly cost (pump, reservoir, infusion sets) – not including CGM-related costsAround $160/month + $7995 initial pump costAround $250/month + $4000 initial pump cost

Final Thoughts

The final choice is based on your or your child’s preference and lifestyle, not to mention your doctor’s advice and insurance coverage.

However, and despite the lack of reviews at this time, the Mobi seems to be superior to the t:slim at least when it comes to weight, size, tubing length and water resistance. On the other hand, the t:slim is still superior when it comes to CGM integration, data sharing and reservoir size.

We’ll definitely be keeping an eye out for the Mobi as it becomes more available on the market, so we can provide a more complete overview of this pump.