A couple months ago I decided it was time for a change.
It had been a long time coming - after years of no significant diabetes incidents, I had three in a two month period. While the Freestyle Libre sensor has been amazing since I started using it in 2015 and I cannot recommend it enough, I (*cough*Everet*cough*) decided it was time for a pump and sensor that talk to each other.
You may recall my adventures with the Medtronic 640G (aka the 630G/670G in the USA). It was one of those "well, it's a nice idea but I kinda hate it" experiences. I ended up switching back to the older version (Paradigm Revel), but then Medtronic decided to stop manufacturing the smaller (180mL) version. So when I had to warranty my pump due to a crack in the reservoir, I got stuck with a 300mL pump, which is significantly bigger. Contrary to popular belief, size does matter, and I couldn't help but feel that Medtronic was focusing on their software and ignoring the actual hardware and what the end users are looking for. The pump is big, the sensor (the current Medtronic sensor is the Guardian) is large... and while the technology is great, it's just too big for my liking.
6 months later and I'd reached a point where the size was just too much.
6 months later and I'd reached a point where the size was just too much.
Enter research mode:
I started with a Google search of "smallest insulin pump" and ended up winding my way to the Tandem t:slim X2, which communicates with the Dexcom G6 CGM. For reference, here are photos of the Medtronic 670G (top left), Tandem t:slim and Medtronic 530G (top right), and the full t:slim and Dexcom G6 setup, with an iPhone SE for scale.
I started with a Google search of "smallest insulin pump" and ended up winding my way to the Tandem t:slim X2, which communicates with the Dexcom G6 CGM. For reference, here are photos of the Medtronic 670G (top left), Tandem t:slim and Medtronic 530G (top right), and the full t:slim and Dexcom G6 setup, with an iPhone SE for scale.
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Obviously, I'd hate to do something the easy way, so I started the pump-swap process at the end of December. Because normal people take holidays, this meant the actual paperwork didn't get started until early January, at which point we were fighting the clock: I'm heading out for field work at the start of February.
The folks at Tandem have been great to work with from day 1. They bought out my Medtronic warranty ($999), made sure that the insertion sets were going to be comparable to what I'd been using, and got things on their way in under a week after making contact. Additionally, their reps are full of useful tips (your pump stops receiving your CGM sometimes? Wear it glass-side-out. BOOM! Problem fixed).
1. Pump shows up at the door. Make really excited noises and explode the box all over the kitchen.
2. Wait 2 days for current infusion set to end. Program all the basal settings into the t:slim.
3. Carefully read the instructions on changing your set. Twice. Because WTF? This is different.
4. Change set and start using fancy new pump.
5. CGM's show up at the door.
6. Put one on, make it talk to the pump, carry on as usual.
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Full disclosure: I did not do a formal orientation on the pump and CGM. Things went kinda like this:1. Pump shows up at the door. Make really excited noises and explode the box all over the kitchen.
2. Wait 2 days for current infusion set to end. Program all the basal settings into the t:slim.
3. Carefully read the instructions on changing your set. Twice. Because WTF? This is different.
4. Change set and start using fancy new pump.
5. CGM's show up at the door.
6. Put one on, make it talk to the pump, carry on as usual.
My point being, if you're not comfortable playing cowboy or are new to the pump-CGM systems, you should really have your doctor/company reps involved. They'll walk you through the system, show you the features, how to use them, change your infusion sets, etc. In short, they're resources that are available and should definitely be utilised.
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Anyways. On to the pump review.
The Features
The big selling point for the t:slim x2 is the ability to anticipate and try to address low BGL before they happen. Medtronic's 670G/Guardian system is the only other pump-CGM system on the market that offers the same features. A neat little comparison between the two can be found here. Note that the major difference as an end user is that the Guardian requires daily manual calibrations, while the G6 does not (although there's an option to enter a calibration if you want to).
The Basal-IQ feature is Tandem's response to Medtronic's predictive suspend. Basal-IQ turns the pump off when it's predictive algorithm predicts your BGL will dip below 80 mg/dL in 30 minutes. The pump also turns off when your BGL dips below 70 mg/dL. It turns the pump back on when the CGM reading increases. If the CGM increases then starts to trend down again, the pump turns itself back off.
Also, you can have multiple basal rate programs that you can switch between at-will. In the Amy-verse, this means you can have a "working" program where you fiddle with basal rates to fine-tune things. Yes, I make awesome choices. No, you probably shouldn't mimic me.
Also, you can have multiple basal rate programs that you can switch between at-will. In the Amy-verse, this means you can have a "working" program where you fiddle with basal rates to fine-tune things. Yes, I make awesome choices. No, you probably shouldn't mimic me.
The Set Change
The reservoir filling is a bit awkward. Where Medronic has a needle integrated into the reservoir when you take it out of the packaging, Tandem's system requires using a syringe to fill the reservoir. Hello, having a sharps container back in my life. The overall set change process is a bit more complicated and time consuming, but the menus are simple and intuitive.
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| The supplies required for a set change of the Tandem t:slim |
My biggest gripe with the t:slim is the complexity of the reservoir/set-change process. There's a lot of room for user-error to introduce air bubbles into the system. The biggest pain in the ass is that the t:slim requires you to pull all the air out of the reservoir before putting the insulin in. The reservoir - tubing connection kinda gets in the way of this.
Also, can we talk for a minute about the weird-ass shape of the reservoir? I get the whole "need-a-patent" thing, but the little connection tubing is a wee bit annoying to work around when filling the reservoir. It looks like a tiny space gun.
Now a word of warning (I'm going to mention this a couple times because it's a big fucking deal):
The reservoir can pop out of the pump when taking it out of the case. The pump case is designed so you can change your infusion set without taking the pump out, but what that actually translates to is that you can accidentally remove the reservoir if you're taking the pump out in and out of the case regularly. Personally, I've been skipping the case during the day and just putting it on so I can clip to my shorts to sleep. Guess how I know about this issue?
Yeah. It keeps happening when I take the case off.
The Sensor
Dexcom managed got FDA-approved for a 10 day wear with no finger stick calibrations on the sensor, which makes the product competitive with the Libre, albeit a bit bigger.
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Left - Freestyle Libre. Right - Dexcom G6  |
For comparison, here's the Medtronic Guardian CGM. Note that everyone I know who uses it ends up putting additional adhesive on over the top of it, so the actual footprint of the sensor is bigger than what Paige is modelling.
I did some mucking around with the CGM alarms until I found something that wasn't going to make me homicidal. In the never-ending battle against alarm fatigue, sometimes it's best to keep it simple. You can turn off the alert when the Basal-IQ kicks on and off to auto-suspend the pump, but you'll always get low/high BGL alerts. Which are really the ones you want.
Update: It's worth noting that there is a hack for the G6 that will let you reset the sensor and get another 10 days out of it. The adhesive doesn't like to last that long without some help, and it's definitely not an approved thing, but it's always worth knowing you can get a little extra out of the sensor if you have to.
Also, there is a known issue with getting a sensor restart error if you change the sensor too fast. According to the tech support folks, you need to wait 5-10 minutes between ending and starting a new sensor to prevent the transmitter/whatever from thinking you're just restarting with the same code. They do send you a new sensor if this happens, but it's a massive and really stupid pain in the butt.
Update: It's worth noting that there is a hack for the G6 that will let you reset the sensor and get another 10 days out of it. The adhesive doesn't like to last that long without some help, and it's definitely not an approved thing, but it's always worth knowing you can get a little extra out of the sensor if you have to.
Also, there is a known issue with getting a sensor restart error if you change the sensor too fast. According to the tech support folks, you need to wait 5-10 minutes between ending and starting a new sensor to prevent the transmitter/whatever from thinking you're just restarting with the same code. They do send you a new sensor if this happens, but it's a massive and really stupid pain in the butt.
Taking Insulin
The first couple days on the t:slim I continued my old ways and entered in the units I wanted to take manually, rather than using the carb and correction calculations and letting the pump do the math.
What I found, however, was that the Basal-IQ would kick on and I wound up yo-yo'ing. Apparently my general rounding wasn't something the system was down with.
Eventually, I decided to use the pump the way it was intended (novel thought, I know). Oddly enough, it seemed to help level out the swings. Besides, taking a bolus is so quick and easy, even when you're using the carb ratios, that it doesn't influence the amount of time you're looking at the pump.
Eventually, I decided to use the pump the way it was intended (novel thought, I know). Oddly enough, it seemed to help level out the swings. Besides, taking a bolus is so quick and easy, even when you're using the carb ratios, that it doesn't influence the amount of time you're looking at the pump.
That said, I've had to adjust the amount of carbs that I use to treat low blood sugar levels. The Basal-IQ suspending the pump means that I ultimately need fewer carbs to turn things around. Cue breaking a 24 year old habit. This is gonna take some time.
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Pros:
- There is a "quick bolus" feature (similar to the easy bolus on Medtronic pumps) that's actually easy to use. For someone who spends a lot of time with their pump in a bra or some other place where you really can't pull it out, this is critical. Also, the pump vibrates when you activate the quick bolus, when it accepts the amount, and when it accepts the bolus. It's a nice tactile cue that things have gone according to plan.
Oddly enough, it's almost just as easy to just pull out the pump to deliver insulin if it's in a pocket, rather than using the quick bolus. That's novel for me, since I've been pocket-pumping for the last 17 years. The bolus feature on the t:slim is just so slick and easy with the touch screen.
- The t:slim is updated via software downloads from your computer. This means that when the FDA finally approves a closed-loop system (or even letting you program boluses from your phone), I'm only a download away from never having to rummage around in my boobs or up my skirt again.
- The pump screen is still readable and easy to use (I'm always wary of touch screens) after being coated in boob sweat during a run. I can't even count the number of pumps I've had to replace due to boob sweat over the years, so that bodes well. Also, no issues with glare or polarised lenses.
- You can get pump cases in fantastic colors. Like blue and pink. It's amazing.
- The pump is super slim without a case and fits easily in a sports bra. It even lays flat! (Disclaimer: you're gonna want to buy a bra with a phone pocket so the pump can stay facing out)
- The pump is super slim without a case and fits easily in a sports bra. It even lays flat! (Disclaimer: you're gonna want to buy a bra with a phone pocket so the pump can stay facing out)
Cons:
- The screen is dark if the pump isn't actively in use, so you can't use it as a watch. I'm going to miss my 'boob clock'.
- The Dexcom G6 adhesive is huge. I get that it's to keep the thing on, but holy crap. Gargantuan. There is no subtlety wherever you put the CGM. On the other hand, no one will ask me if it's a nicotine patch... so one up on the Libre?
- The G6 transmitter was designed to transmit to something with a fairly powerful receiver (aka a phone). Unfortunately, the t:slim receiver isn't nearly as powerful as the phone, so there's a pretty significant line-of-sight effect between the CGM and pump. Basically, the pump needs tobe on the same side as the sensor with have the glass facing out to consistently pick up the CGM. Given Dexcom's history of being responsive and releasing updates to their tech fairly frequently, I have a hunch this will be addressed in the next version of the CGM. (Update: after much field work, I've decided that it's the pump case that's the issue. As long as the pump is screen-out, it talks to the CGM)
- You have to disconnect to take the pump clip/case on and off. Kinda annoying (but not the end of the world). However, it's easy to accidentally remove the reservoir taking the case off. You can just push the reservoir it back in and all is good (no priming required), but if you're not paying attention and looking for it, it would be scarily easy to not realize your reservoir wasn't actually installed.
- The tubing comes in 23" (aka really short so don't drop the pump) or 42" (aka long enough to take up fancy knot tying). A nice 32" tubing would be perfect.
- The connection between the reservoir and tubing is definitely the weak point in the system. If the pump is stuffed in a bra (or upside down in a pocket,or whatever) for long periods, the tubing kinks a little and you get No Delivery alarms. Straightening out the connection so the tubing runs straight in/out of it fixes the problem, but what it means in practice is that you need a bra with a pocket or pouch so the pump orientation can be fixed to avoid kinking the connection.
- The G6 transmitter was designed to transmit to something with a fairly powerful receiver (aka a phone). Unfortunately, the t:slim receiver isn't nearly as powerful as the phone, so there's a pretty significant line-of-sight effect between the CGM and pump. Basically, the pump needs to
- You have to disconnect to take the pump clip/case on and off. Kinda annoying (but not the end of the world). However, it's easy to accidentally remove the reservoir taking the case off. You can just push the reservoir it back in and all is good (no priming required), but if you're not paying attention and looking for it, it would be scarily easy to not realize your reservoir wasn't actually installed.
- The tubing comes in 23" (aka really short so don't drop the pump) or 42" (aka long enough to take up fancy knot tying). A nice 32" tubing would be perfect.
- The connection between the reservoir and tubing is definitely the weak point in the system. If the pump is stuffed in a bra (or upside down in a pocket,or whatever) for long periods, the tubing kinks a little and you get No Delivery alarms. Straightening out the connection so the tubing runs straight in/out of it fixes the problem, but what it means in practice is that you need a bra with a pocket or pouch so the pump orientation can be fixed to avoid kinking the connection.
Wait and See:
- I'm not sure how I feel about this super basic pump clip. It's all but impossible to clip onto a real bra, but does seem to hold pretty well to sports bras and leggings. On the other hand, you have to disconnect your pump to pull the tubing through it to take it off. I've found myself wearing the pump without the clip around town because it's so slim it fits in my girl pants pockets so well you can't even see it.
- The pump is rechargeable and theoretically can charge to a safe level while you're in the shower. After running it down to 10% (FYI, it starts yelling at you below 25%), it took around 30 minutes to charge to 50%, and another 30 or so to get all the way to 100%. Topping up the charge every couple days or when you disconnect to shower is definitely a good way to keep from needing an emergency charge. I made it about 5 days on a CGM before I had to charge it.
Next question: will I be able to charge it using power packs/portable batteries while hiking or camping. (Update: yup, you can charge the pump off a power pack. Yay!)
Next question: will I be able to charge it using power packs/portable batteries while hiking or camping. (Update: yup, you can charge the pump off a power pack. Yay!)
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The Verdict
Thus far, I've been really impressed with the ease of the transition to the t:slim and G6 system. The pump itself is intuitive, small, and the customer support has been fantastic. The G6 has insanely large adhesive, but the integration with the pump is good and the adhesive stays on for the full 10 days. My biggest gripe is that the pump and sensor need to be on the same side of your body to ensure transmission. I went into this fully prepared to hate the reservoir-tubing connection being a couple inches off the end of the pump. Much to my surprise, it's been pretty much a non-issue as far as getting in the way and catching on things. Although I do live in fear that it'll somehow unscrew itself. (Update: the only issue I've found with the connection is the aforementioned No Delivery due to kinking at the connector. Easily solved with pump placement, but an inconvenience if you don't want your pump in a pants pocket for reasons such as, say, not wanting to damage it when you're swinging around 80 lbs augers and bracing them on your leg.)
I definitely have to adapt my management habits to accommodate the Basal-IQ and all that fun stuff. For people transitioning from the Medtronic system, this will likely be a non-issue. For those of us who have been stubbornly refusing to relinquish any kind of control, change is hard.
Thus far, I've been really impressed with the ease of the transition to the t:slim and G6 system. The pump itself is intuitive, small, and the customer support has been fantastic. The G6 has insanely large adhesive, but the integration with the pump is good and the adhesive stays on for the full 10 days. My biggest gripe is that the pump and sensor need to be on the same side of your body to ensure transmission. I went into this fully prepared to hate the reservoir-tubing connection being a couple inches off the end of the pump. Much to my surprise, it's been pretty much a non-issue as far as getting in the way and catching on things. Although I do live in fear that it'll somehow unscrew itself. (Update: the only issue I've found with the connection is the aforementioned No Delivery due to kinking at the connector. Easily solved with pump placement, but an inconvenience if you don't want your pump in a pants pocket for reasons such as, say, not wanting to damage it when you're swinging around 80 lbs augers and bracing them on your leg.)
I definitely have to adapt my management habits to accommodate the Basal-IQ and all that fun stuff. For people transitioning from the Medtronic system, this will likely be a non-issue. For those of us who have been stubbornly refusing to relinquish any kind of control, change is hard.
