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

Last modified on May 21st, 2024

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.

If you need help with diabetes nutrition, check out these free resources:

6 thoughts on “Tandem t:slim X2 with Control-IQ: Insulin Pump Review”

  1. The T-Slim pump has both specific pros and cons, but when you view it as a total system, it is in my opinion a frustratingly inflexible and annoying Rube Goldberg-style engineered piece of junk. Functionaly, I think it is like an aircraft autopilot that works great right up to the point when it flies you into the side of a mountain.

  2. This pump has some really good features but the construction of this device is not very good. After about a month of use the cartridge wouldn’t snap into place and they said you need to get the little rings on the inside of the unit off the silver sphere. Yeah right doesn’t come off and why would you build a system like that not to mention the damage you could do. The infusion sets are always bending not only after you put it in but when you open them the needle is bent. There’s other things they need to work on but that takes a long time. And of course the insurance companies don’t want to replace defective parts.

  3. Due to the excessive cost of tresiba which I’ve used for a long time I finally gave in to using a pump. I’ve heard a lot of good reviews of CIQ but seriously?
    1. App constantly disconnects. I don’t want to fiddle about with the pump itself.
    2. App lacks features and capabilities and if you need to create a new profile for example you must use the pump.
    3. App constantly disconnects. I swear I’m re/pairing the pump at least 3x per day. Also can’t walk away from my phone and I hate having to carry both all the time.
    4. Being plugged into the wall daily for 15 minutes as recommended is extremely annoying. Also I plan to go camping for a week. At least my truck has AC outlets.
    5. Five screens to do a bolus? I can draw and take insulin in the time it takes to put my code in (and yes I know this is a stupid FDA requirement.)
    6. What happened to seven?
    7. Just kidding.
    8. Exercise mode has to be turned on at least 45 minutes before a long bike ride I guess. I don’t always plan my bike rides that far in advance. Tried it once and only got halfway through my ride before I had to eat half a bag of jellybeans.
    9. Carrying this stupid thing is extremely inconvenient. Sleeping with it? Even more inconvenient. Have to buy a bunch of sleepwear with pockets to keep it in place as I roll around at night a bit.
    10. Can’t turn alerts off completely as CIQ will alert you constantly. Vibrate mode is still annoying.
    11. I’ve been taking shots for 45 years and my A1c was in the 5’s pretty consistently the last two years before the pump. Take insulin and go, no big deal. Adjust as needed. Now however I spend at least an hour or two a day fiddling with this damned pump to get it adjusted for whatever is going on. Yes I know I can make more profiles (and will eventually) but it’s a hassle to do so on the pump.
    12. The waste of 100’s of units of insulin a month is huge with as over priced as it is. As well Humalog and I do not get along very well (Lispros don’t generally work well for me and never have though they are better than R and NPH (barely.)) Sadly my insurance is junk and ExpressScripts/CVS are extortionists.
    13. Time In Range. Before the pump I was pretty consistently at 83-85% and only had a high over 250 about once a month. So far I’ve had multiple highs over 250 with the pump even though my TIR is slightly higher. Honestly 5% more TIR is not worth the hassle of dealing with this device. Some of this of course is due to needing to tweak the pump to my specific needs but still frustrating.

    I could go on but honestly I’m not impressed with the pump. The only reason I’ll continue is my insurance covers it 100% with no copay and tresiba is 200 a month which I can’t afford.

Leave a Comment

Your email address will not be published. Required fields are marked *

Shopping Cart
Scroll to Top