Tandem t:slim X2 with Control-IQ: Insulin Pump Review

Title of article against a white background with insulin pump and supplies pictured above title and lemons below title
Choosing an insulin pump is an important decision in your diabetes journey. If you’re completely new to pump therapy, I recommend first reading my other blog post, Diabetes Insulin Pump: A Complete Guide to Getting Started. Once you know more about insulin pumps, then read my Tandem t:slim X2 insulin pump review.

**Disclaimer: This review is based entirely upon my own opinion/experience after using this insulin pump system for the past 2 years. For writing this blog post, I will not receive any compensation from Tandem. This blog post is for general informational and educational purposes only and is not intended to treat, cure, or diagnose any disease. The information in this post is not a substitute for medical care or advice provided by your healthcare team. Please consult your doctor for specific, personalized treatment.**

Insulin Pump Supplies

Like most insulin pumps, Tandem’s pump supplies consist of an insulin cartridge and infusion set. Syringes are included in your box of insulin cartridges as you need to use a syringe to fill them with insulin.

And of course, you’ll also need a vial of fast-acting or ultra-fast acting insulin. You can read more about insulin for pumps over at Diabetes Strong.Photo showing the needed Tandem insulin pump supplies: syringe, infusion set, insulin cartridge, and insulin


Let’s first review the pros about the Tandem t:slim X2 insulin pump.


Control-IQ is Tandem’s automatic insulin adjustment technology. The pump talks with the Dexcom G6 CGM every 5 minutes and predicts what your blood sugar will be 30 minutes ahead of time.

The pump will then increase, decrease, or suspend basal insulin delivery to keep blood sugar in between 112.5 and 160 mg/dL. Also, if your blood sugar is predicted to be at or below 70 mg/dL, Control-IQ automatically suspends basal insulin delivery.

This technology is designed to keep your blood sugars in range much longer than if you were manually making insulin adjustments on your own. Control-IQ bases treatment decisions off future blood sugars. It’s doing the work to try and prevent lows and highs before they happen.

That is a definite pro!
**It’s important to note that Control-IQ does not do EVERYTHING for you. Carb counting and diabetes self-care skills along with attending regular healthcare provider(s) visits are all part of using this and any insulin pump system.** 

Activity settings

Using Control-IQ gives you the option to use the activity settings: Sleep & Exercise.

Sleep Activity

If you have trouble sleeping due to waking up to treat high and low blood sugars, the Sleep Activity is for you. With the Sleep Activity turned on, Control-IQ adjusts basal insulin delivery to keep your blood sugars between 112.5 and 120 mg/dL.

It really is so nice getting a full night’s sleep without being woken up by a beeping CGM alerting you to a low blood sugar.
You have the option to set one or two sleep schedules so that the Sleep Activity will turn on and off automatically. You can also choose to do this manually. For the Exercise Activity, you’ll need to turn this on and off manually.

Exercise Activity

When the Exercise Activity is turned on, Control-IQ adjusts basal insulin delivery to keep your blood sugars between 140 and 160 mg/dL. It also stops basal insulin delivery when blood sugar is predicted to be less than or equal to 80 mg/dL.

Even though this feature is called, “exercise” it’s not meant for just that. Think of all the activities that have lowered your blood sugar. Cleaning the house, shopping, push mowing, and waitressing can all be examples of an activity that may lower blood sugar. Having the Exercise Activity turned on during those times is great for preventing lows and highs.

Software updates

The way you update your pump is another Tandem insulin pump pro.

With Tandem, you don’t have to replace your pump to get an upgrade. Software updates can be done in your own home using the t:connect portal and your computer. Who doesn’t like getting to do things from the comfort of your own home?! In fact, Tandem just rolled out a new software update.

Bolus from your phone

The newest software update from Tandem allows pump users to bolus with their cell phones (if the cell phone is compatible).

If you have the pump and need to do the software update, you simply login to your t:connect portal, complete the assigned ~30 minute training, and plug your pump into the computer.

I don’t know about you, but I definitely wish this software update was available before my wedding day three years ago. Imagine trying to reach your pump to bolus while wearing a wedding gown in front of hundreds of people! It would’ve been so much easier to use my phone.


Speaking of phones, did I mention this pump uses a USB power cord for charging just like a phone? Tandem even sends you a super long power cord with your pump kit. This comes in really handy when your power outlet is far away from your comfy chair.

Best practice is to charge your pump every day for about 10 minutes. I’m pretty impressed with the battery life though. Normal pump use allows a full battery to last for about 5 days before you absolutely need to charge it.


Every product comes with some cons. We’ll next review the cons of Tandem’s insulin pump.

Only compatible with Dexcom

Tandem only works with the Dexcom G6 CGM which kind of stinks. Especially when maybe your insurance isn’t the best at covering the Dexcom. You may need to use a different CGM or switch to a glucometer instead. Without the Dexcom, Control-IQ will not work, but you can still use the pump.

Filling the cartridge

Filling the insulin cartridge is the biggest con I’ve noticed since using this pump. The process involves filling a syringe with insulin, then inserting the needle of the syringe into a tiny white circle on the cartridge. You can see the white circle in the photo below.Infographic of insulin cartridge explaining where the syringe needle is inserted into to fill the cartridge with insulin
The process doesn’t stop there. Next, you need to get rid of the air bubbles by pulling up on the syringe plunger while it’s inserted in the cartridge, and then let the pressure suck the plunger back down.

You then remove the syringe from the cartridge and push the air bubbles out of the syringe using the plunger. Finally, you repeat the process of sticking the needle of the syringe back into the tiny white circle on the cartridge and filling it with insulin.

This whole process would be very challenging for a person with vision impairments or hand use trouble.

Target blood sugar customization

Finally, when Control-IQ is on, you cannot set your own target blood sugar. The automatic target blood sugar stays at 110 mg/dL.
This is honestly a great target, but, if you are pregnant and using an insulin pump, your target needs to be lower. It would be nice to be able to customize the target blood sugar for that kind of situation.


If you’re thinking about starting pump therapy or switching to a different pump, definitely consider the Tandem t:slim X2 with Control-IQ.
Download the t:simulator App on your phone and try out the pump’s touch screen. Tandem also has a 90-day return policy, so you really have nothing to lose by trying out this pump.

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