A 5-Month Review of the Tandem t:slim X2

I began using the Tandem t:slim X2 insulin pump in mid-December. In February I wrote a mostly-favorable review of the pump, but indicated that I was struggling with user-error problems and occlusion alarms that stopped insulin delivery. In March I wrote a post indicating that I had found a solution to the false occlusions, but it may have been a premature claim to success. I am now 5+ months into using the pump and thought I’d give an update on my experiences.

Overall Satisfaction:

I am happy with my Tandem pump.

The things I liked before I still like. I enjoy the contemporary looks of the pump and the touchscreen menu navigation. I appreciate being able to fine-tune settings although I don’t always take advantage of that capability. I like being able to easily see my Insulin on Board with one button push. I like that I can see the pump screen when outside in bright sunlight.

I have trained myself to avoid most of the user-error problems that I previously discussed. After filling the cannula of a new infusion set, I patiently wait until I arrive at the screen to resume insulin. I still get occasional Incomplete Bolus alarms when I put in a BG number to see if I need a correction. If I don’t need a correction I often forget to back out of the bolus menu and end up with an alert. I now get an A+ in remembering not to detach my pump in the middle of a bolus. It has been an adjustment moving from the fast bolus delivery of Animas pumps to the delayed delivery of a t:slim, but I have adapted.

Still Annoyed:

I still hate the pigtail on the pump tubing. It often makes the tubing stick out of my pocket which is unsightly and a doorknob risk. I also dislike how long it takes to fill a cartridge. I know that the X2 is faster than the original t:slim, but it is not a one or two minute task as with previous pumps.

Tandem recently announced that it will convert the luer lock connector at the pigtail to a proprietary connector called the t:lock. The purpose of this change is to reduce the time and insulin required to fill the cartridge and tubing. The downside of this conversion is that only Tandem proprietary infusion sets will be compatible. For me that is no problem because I use Comfort Shorts, a Tandem-supported set. I also understand that this change should help Tandem’s financial bottom line and I can’t oppose that. Some t:slim users, particularly those using non-supported sets such as the Cleo, Orbit 90, and Animas Inset, are enraged that Tandem is going the Medtronic route of proprietary sets.

I continue to dislike the Min Basal alerts. They happen a minute or two after I have set a temporary basal of zero and are annoying. I suspect that the alerts are the pump sensing the basal amount rather than the result of what I have just programmed. So maybe it is a safety issue. But it’s still annoying. If the pump questioned my temp basal amount right away, it would be better than interrupting me a few minutes later. At least this alert doesn’t stop insulin delivery, so it stays in the “annoyed” category.

Avoiding Occlusion Alarms:

When I wrote my initial review of my t:slim X2, I was unnerved by the fact that I was experiencing weekly occlusion alarms that resulted in a stoppage of insulin. Having pumped for 12 years with no such alarms, I knew that they were false and related to the pump not my infusion sets. In March I wrote a blogpost describing what I thought was a workable solution to the problem. I began using a Nite Ize clip and keeping the pump out of my pocket. The blogpost of course jinxed me and I had 3 occlusion alarms the next week. However, in fairness to Tandem, those alarms all happened with the same infusion set and maybe it was a site problem.

When I flew back to Minnesota in mid-April, I set off the TSA metal detector. As a PreChek traveler I am used to never declaring my pump and speeding through security. The downside of the Nite Ize clip is that it can’t be removed and ensures an airport pat-down every time. Because I set off the metal detector on my only other flight with the t:slim, I am afraid that the pump itself might have enough metal to always alarm, but I hope not.

I decided to remove the Nite Ize clip which wasn’t tight enough anyway. I wanted to go back to carrying the pump in my pocket and knew that doing that without a case was a recipe for occlusion alarms. Meanwhile a Tandem tech suggested the removable part of the t:slider case for use in my pocket. He indicated that the occlusions were a temperature problem and this case would resolve that. It is essentially a t:clip case without the annoying clip. I have used this case with my pump in my pocket for 6 weeks without a single occlusion alarm. For working out I put the pump in a Running Buddy Mini case on my waistband.

I made one other change that might be responsible for eliminating occlusion alarms. Rather than follow the Tandem instruction video for filling my cartridge, I do two things differently. After pulling air out of the cartridge with the insulin-filled syringe, I do not release the plunger as instructed. I hold it tight so that the air stays at the top of the syringe as I remove it. Then as directed I hold the syringe with the needle up and tap it so that all air moves to the top. At this point, I reinsert the syringe into my insulin vial and slowly push the air bubbles back into the vial. When there are no more air bubbles, I pull in enough insulin to measure my desired amount. If I see more air bubbles, I repeat the process. This eliminates the messy loss of insulin when shooting the bubbles out into the air.

I have not done a scientific test to determine whether it is the new case or the alternative method of filling the cartridge that is working for me. All I know is that with the combination of the two changes, I have not had a single occlusion alarm in 56 days.

Please note that the t:slider case is sold out according to the Tandem store although I wonder if the tech reps still have access to them. A new case to replace the t:clip case is in the works but I don’t know when it will be available.


One change I would like to see is the ability to customize the preset temporary basal setting. It always reverts to 50% now and 50% over 2 hours. That is a preset I never use and I override it every time. I would like the option to program my own preset or to at least show the last-used setting. This should just be a software change, so maybe it could be a future fix.

I anxiously await the software update to integrate my Dexcom G5 into the pump. Because it looks as though CMS will not allow the use of a smartphone with sensors purchased under Medicare (stupid for sure!!!), it would be nice to have my CGM as part of my pump even if I have to carry the Dex receiver also. I haven’t heard anything on when this update will be released.

My Favorite t:slim Hack:

I live in an older house and have few electrical outlets in convenient locations. Many people charge their t:slim pumps while showering. Our bathroom has only one outlet that is overused with hair dryers, a straightening iron, razors, and electric toothbrushes. I can sit near an outlet in the family room while watching TV, but then it is a PITA to unhook myself when I get up to do something. Charging in the car works fine when I remember to do it.

My newest solution is to use an Anker PowerCore back-up battery which I bought this winter for hiking. After owning it for a month or two, it dawned on me that I could use it to charge my pump! I keep a compatible cord attached to the Anker device and just plug in when needed. I can tuck the charger in my pocket or waistband and move about the house as needed. The charging is just as fast as from an outlet.

A great solution to a minor problem.


I am satisfied that I chose a Tandem pump in late 2016 and think that I would make the same choice again. The only serious problem I have had with the pump is false occlusion alarms and that has mostly become a non-issue. The constant rumors about Tandem’s financial status are concerning, but my fingers are crossed that the company will overcome its problems and remain an innovative player in the diabetes tech world.

Winning the Battle with Tandem Occlusion Alarms

I began using the Tandem t:slim X2 in mid-December and wrote a product review in February. At that point I was frustrated with what I called #FakeNews occlusion alarms. I described the situation:

“I have used the Tandem t:slim X2 for almost 10 weeks. In that time I have had 9 occlusion alarms resulting in an immediate stoppage of insulin delivery. The first couple of times I panicked at the shrieking pump alarm fearing that something was actually wrong. Nope. Not once has there been a problem that did not disappear by working my way through the menu screens and pressing “Resume Insulin.” The vast majority of these alarms have been while delivering meal boluses, but not all.”

I mentioned that I had tried several recommendations from both Tandem reps and t:slim users on Facebook. Because I was using cartridges for more that the recommended 3 days, I began changing them more frequently. Instead of reducing the number of occlusion alarms, more frequent changes with less insulin in the cartridge resulted in more alarms. I tried carrying my pump in a Spibelt and then a Flipbelt as one D-friend recommended. I found the belts uncomfortable for everyday use and was quick to abandon them when I got an occlusion alarm wearing one.

A Tandem tech gave me a call and indicated that he is convinced that these occlusions happen because of temperature changes. He wanted me to start using a Tandem case to protect the pump from temperature changes when it was taken out of my pocket or Spibelt. He promised to send me a case without the clip so that I could carry the pump in my pocket. Meanwhile I started using the dreaded t:clip case which was bulky and ill-balanced and frequently fell off my waistband. I used the case for a week and hated it despite having no occlusion alarms. I took it off for a day hike and immediately had another lunchtime occlusion alarm.

Very quickly I reached the point that I was going to wear the pump the way I wanted to and occlusion alarms be damned. I wasn’t going to use an uncomfortable waist pack. I wasn’t going to use the t:clip case which ruined the elegant size and looks of the pump. I wasn’t going to change the cartridge every 3 days and waste a ton of time and insulin doing so.

Meanwhile I recalled that both Sarah “Sugabetic” and Kerri Sparling had written about a metal clip that could be attached directly to the pump. I reviewed their blogposts and ordered a Nite Ize Hip Clip from Amazon. I was a little spooked about attaching something directly to the pump, but went ahead anyway. For the first time I felt that I finally had a solution to carrying my X2 that would take it out of my pocket but keep the sleek lines of the pump intact.

I started using the Hip Clip on February 15 and made it 17 days before I had an alarm during a mealtime bolus. Although the pump was on my waistband, it looked as though the tubing was bent over on itself. Not exactly kinked but somewhat bent. I straightened the tubing and resumed insulin with no problems. As of today I have made it 32 days with only the one occlusion alarm.

Meanwhile I have not had to use the bulky Tandem case. I have not had to wear a Spibelt or Flipbelt except when I choose to at the gym. I have continued to use each cartridge well past the 3-day recommendation. (I change the infusion set every 2-3 days, just not the cartridge or tubing.) I have been happy wearing the pump on my waistband and been particularly happy that the pump retains it beauty and small size.

I am wearing and using the pump the way I want to wear it and the way I want to use it.

What has been my solution?

  1. I wear the pump with the Hip Clip clipped to my waistband most of the time. I try to make sure that there is no pressure on the tubing to cause it to bend near the pump and tubing connector.
  2. If I carry it in my pocket (which is easy to do because the clip is so small), I make sure that during boluses I keep the tubing near the pump and pigtail straight.

This solution seems to work for me, but will it work for others experiencing occlusion alarms? Are those of us experiencing the alarms having them for the same reason? I can share my profile: low average daily dose of insulin (<20 units), thin-average build, using manually-inserted Comfort Short infusion sets, carrying the pump in pocket with no case, using each cartridge for longer than 3 days. From Facebook discussions I don’t find a lot of overlap with my profile compared to others. I don’t even know what percentage of t:slim and X2 users experience occlusions because discussions about occlusions primarily attract users having the problem. Many Tandem pumpers report having no occlusion alarms. Some pumpers who report occlusion alarms believe that they are really having occlusions and have been helped by switching type of infusion sets. But that is not the case for many of us.

So for now I have learned to live with and mostly avoid occlusion alarms with my Tandem t:slim X2. IMO there is a flaw somewhere in the design of this pump system because I strongly believe that I should be able to carry my pump in my pocket without alarms. Tandem also thinks so because this screenshot of the t:slim X2 webpage shows a pumper pulling an uncased pump out of her pocket.

On March 8, 2017 Tandem announced that it will soon implement infusion sets and cartridges using a newly-designed tubing connector. The news release states:  “The new design reduces the time required to fill the infusion set tubing by approximately 30 seconds and reduces the amount of insulin used in the process by approximately four and a half units.” There is no mention that the t:lock Connector will reduce false occlusion alarms and it probably won’t, but a girl can always keep her fingers crossed….

In summary, I seem to have figured out how to avoid occlusion alarms on my Tandem pump. Maybe it is the tubing; maybe it is the temperature issue. Whatever. For the most part I’m just not thinking about it. And that’s a good thing.


Please note that this post only reflects my personal experiences. Be sure to talk with a Tandem representative and read as many reviews as possible if you are in the market for a new pump.

A Review of the Tandem t:slim X2

Laddie_Head SquareI started using the Tandem t:slim X2 insulin pump on December 13 and this review is long overdue. After 2 months, I am mostly happy with the pump. I am comfortable navigating through the menus and have learned a few shortcuts. I like the touchscreen and the “modern” look of the pump. I like knowing that I will be able to add new features to my pump with software updates. At the same time I am annoyed with almost daily alerts about one thing or another. Most significantly, I am frustrated with occlusion alarms which I never experienced with previous pumps.

The Good Things

I like the touchscreen and being able to enter numbers for carbs and BG levels rather than scrolling up and down.

I like the looks and size of the X2.

I like the ability to turn off the screen to preserve battery life. I like the ability to go backwards through menus and tap the “T” to return to the home screen.

I like being able to fine tune settings. For example with Active Insulin Time, my early Medtronic pumps restricted changes to hours. 3 hours seemed too short; 4 hours seemed too long. Then with Animas, I could select 3-1/2 hours or 4 hours and neither seemed perfect. Now with Tandem, I am using 3-3/4 hours and could even select 3 hours and 39 minutes.

I like the ease of setting Site Reminders on my X2. This wasn’t a feature that I particularly missed on previous pumps, but now that I have it, I use it often.

I like that the reservoir icon remains red after I clear the customizable low reservoir alert.

I like that I can read the pump screen in bright sunlight when hiking. Sometimes I have to take off my sunglasses to read it, but it is much better than my Animas pump screens which were totally unreadable.

I like that Tandem has attempted to create a pump that is contemporary and has worked to creatively meet the needs of insulin users.

I like that I will be able to download software updates to add new features such as CGM integration to my X2 as they are released by Tandem. My fingers are crossed that these updates will be allowed under Medicare rules.

I really like this pump.


The Annoying Things

I find filling the reservoir to be an overly complex and time-consuming process. It is like a “black hole” because I can’t see the insulin in the reservoir or troubleshoot air bubbles. I dislike that the icon on the home screen does not give me a more exact estimate for the number of remaining units of insulin. I can start with a syringe of 250 units and the pump registers 180+ units. After delivering 10 units of insulin (that’s half a day for me), it displays units of insulin rounding to the nearest 5 units. Below 40 units it begins to show specific units. I seem to “lose” more than the 45 (!) units that Tandem indicates as normal.

There are alerts which interrupt me on almost a daily basis. I use temp basals of “0” often for 30-60 minutes when I am moderately low and don’t want to eat. Unfortunately the X2 alerts 2 minutes later to indicate that my basal rate is less than half of my normal basal rate. Well, duh! That’s what I programmed. I suspect the alert is actually a result of a sensor, but IMO software should dismiss the alert if the basal change had been programmed.

I dislike the pigtail connection between the cartridge and the tubing. It tends to stick out and cause tubing to hang out of my clothes.

The t:clip vertical case that accompanies the X2 is bulky and poorly balanced. My guess is that it was designed by men who wear it on a belt. When I clip it to my waistband, the pump is top-heavy and leans forward resulting in an odd bulge in my clothing. If I bend over, it frequently falls off. Rumor is that a new case will be released soon.

Things to Which I am Indifferent

I have never wanted a rechargeable pump but it doesn’t bother me. The X2 charges quickly and does not require a proprietary charger. I can even charge it in my car. So it’s fine.

A lot of people like the way that basal and bolus settings are programmed together in blocks of time on the t:slim. So far I don’t find much benefit doing it that way but I don’t care.

The X2 holds 300 units of insulin. I was fine with 180-200 unit reservoirs, but it’s easy to fill the cartridge partway.

User Error Problems

Some of my issues with the X2 have been due to “user error” and are resolving as I become used to the differences between the X2 and my previous pumps.

The most common error that I make is not resuming insulin after filling the cannula on new infusion sets. I can’t quite remember how it was handled with Animas, but I never had the problem of not resuming insulin. With the X2 I have to wade through a couple of screens like “Stopping Fill” and “Test BG in 1-2 hours” before I get to the option of “Resume Insulin.” Many times I have returned the pump to my pocket before those extra screens. Thankfully I always get an alarm that the pump is not delivering insulin and can fix the problem. I am getting better at slowing down and not forgetting to resume insulin, but occasionally I still mess up.

Another annoyance is if I accidentally touch Bolus on the home screen (and this is easy to do) and don’t clear it, I will get an alert for an incomplete bolus although I haven’t entered any data. The alert will not clear until I go back into the pump, clear the alert, and back out of the bolus feature. Once again this is happening less often as I become more focused when handling the pump with an active screen and being sure to push the top button to turn off the display.

I used Animas pumps for the last 4 years and bolus insulin is infused quickly and immediately. Tandem pumps use a patented “Micro-Delivery” process and can take a couple of minutes to infuse a bolus. More than once I have pulled the same trick that used to mess me up with Medtronic pumps. I bolus for my breakfast while getting dressed. Forgetting that I programmed a bolus a minute ago, I unhook my pump to thread the tubing through the hole in my pocket or even to take a shower. Meanwhile insulin is dripping out and I have no way of knowing how much of my bolus I missed. Once again I am working hard to break this habit.

Occlusion Alarms – The Elephant in the Room

I have used an insulin pump since 2005, first Medtronic and then Animas. In all of that time I had at most 2 or 3 occlusion alarms. If you want to add “loss of prime” alerts on my Animas Ping, maybe you could add 5 more alarms. In 12 years I estimate that I had a problem with insulin delivery 7-8 times. Less than once a year. I cracked pump cases more times than I can count, but I never had a pump replaced because it did not deliver insulin.

I have used the Tandem t:slim X2 for almost 10 weeks. In that time I have had 9 occlusion alarms resulting in an immediate stoppage of insulin delivery. The first couple of times I panicked at the shrieking pump alarm fearing that something was actually wrong. Nope. Not once has there been a problem that did not disappear by working my way through the menu screens and pressing “Resume Insulin.” The vast majority of these alarms have been while delivering meal boluses, but not all.fullsizeoutput_1c6b

Before I go any farther, I must admit that I do not change my cartridges every 3 days as recommended. (I do change infusion sets every 2-3 days.) My first occlusions happened when my cartridges had been in use for 8, 9, and 7 days. So I shortened my cartridge use and had occlusion alarms at cartridge ages of 2, 5, 7, and 1 day. I have only used one cartridge without an occlusion alarm. FYI my total daily insulin dose ranges from 13 units to 26 units and averages 18-20 units. I regularly used reservoirs for 8 days with both Medtronic and Animas and never had a problem.

I have been in contact with both people at Tandem and “experts” in the diabetes online community and have considered every suggestion. I have changed cartridges more frequently. I have used a Spibelt and a Flipbelt. I have used the awkward Tandem case because Tandem techs think it is a temperature issue. (I did learn that the case traps in heat and your insulin goes bad in about 5 days.) I have carried the pump in my pocket and worn it on my waistband. I am 100% convinced that my manually inserted Comfort Shorts (Silhouettes) are not the problem. The occlusion alarms have not correlated with site age and have randomly occurred at site ages of 1, 2, and 3 days. I have had no failed or kinked sites and have used these sets for 12 years with no issues. A Tandem tech assured me that the pigtail design of the cartridge/tubing is not at fault because an internal coil protects it from kinking.

Replacing the pump has not yet been requested by me or suggested by anyone at Tandem. I am currently wearing the pump on my waistband using a Nite Ize hip clip attached directly to the pump and I will see if I can make it 2 weeks without an occlusion alarm. (Thanks Sarah Sugabetic and Kerri Sparling.) My record is 13 days; so far I’m on Day 6.

One thing I must give kudos to Tandem on is that when I get an occlusion alarm during a bolus, it does let me know how much of the bolus was delivered so that I can reprogram the rest after clearing the alarm.

Everyone at Tandem has been respectful and concerned. I sit here in the middle of this experience wondering “What separates the many people who never have occlusion alarms from those of us who are plagued with them?” For me these alarms are #FakeNews and #AlternativeFacts and not once have I seen a kink in my tubing or needed to change out an infusion set or cartridge to resolve the issue.


I like my X2 and do not regret the purchase. I wrote extensively about why I chose this pump and I would not make a different decision today.

At the same time I am conflicted about wholeheartedly recommending this pump to others. How can I recommend a pump that averages a once-a-week stoppage of insulin for seemingly no reason? I admit that I don’t follow all of the rules, but in general I am a conscientious PWD and am doing nothing differently than I did with Medtronic and Animas. Because I have always heard the occlusion alarms, I have been able to restart insulin delivery immediately and have suffered no ill effects from these events.

I delayed writing this pump review because of the occlusion alarms. My hope has been that every “fix” would resolve the issue and I could write a glowingly positive review of the X2. I want to love this pump and I want Tandem to grow and be a successful pump company. As I said before, I really like this pump.

Maybe the hip clip will be the solution.

If not, I will probably argue for a replacement pump as the next step. At this point I am confident that I will not be abandoned by Tandem.


Please note that this review only reflects my personal experiences. Many users do not experience occlusion alarms with the t:slim X2. Others had these problems with other brands of pumps and don’t with Tandem. Be sure to talk with your medical team, contact a Tandem representative, and read as many reviews as possible if you are in the market for a new insulin pump.