After much excitement (and anticipation), Tandem rolled out their fancy new hybrid closed-loop insulin pump - CGM system, aka Control-IQ. Obviously, I was super excited to try it out and wasted no time in getting my hands on it.
I figured I'd give it a month or two to put it through its paces before writing a review. It's worth noting that aside from some minor interface changes (which improved the intuitiveness of the system), my original review of the t:slim x2 still applies.
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Closed Loop Systems
I'd like to take a moment to point out that Tandem works with Dexcom, who has been working with other insulin pumps (notably Omnipod) to make closed-loop systems available on a multitude of systems. This is a huge step for making diabetes management systems more widely available for people with pumps still under warranty or who don't want to switch systems. The big push for an FDA-approved loop system that allows diabetics to create a closed-loop system on a variety of insulin pumps and CGMs is being spearheaded by Tidepool, who is working with a multitude of manufacturers, including Dexcom, Omnipod, and a couple unnamed pump manufacturers (who I'm sure includes Tandem) to create an iOS-available closed-loop app. A short but worthwhile discussion on this and potential ramifications can be found here.
Also, in case you missed it, the Control IQ software is interoperable, meaning it's compatible with hardware from other manufacturers. Additionally, the Control IQ algorithm was approved by the FDA, rather than a stand-alone device like the Medtronic 670G.
I'd like to take a moment to point out that Tandem works with Dexcom, who has been working with other insulin pumps (notably Omnipod) to make closed-loop systems available on a multitude of systems. This is a huge step for making diabetes management systems more widely available for people with pumps still under warranty or who don't want to switch systems. The big push for an FDA-approved loop system that allows diabetics to create a closed-loop system on a variety of insulin pumps and CGMs is being spearheaded by Tidepool, who is working with a multitude of manufacturers, including Dexcom, Omnipod, and a couple unnamed pump manufacturers (who I'm sure includes Tandem) to create an iOS-available closed-loop app. A short but worthwhile discussion on this and potential ramifications can be found here.
Also, in case you missed it, the Control IQ software is interoperable, meaning it's compatible with hardware from other manufacturers. Additionally, the Control IQ algorithm was approved by the FDA, rather than a stand-alone device like the Medtronic 670G.
Control IQ vs. Medtronic 670G
Unsurprisingly, there are already well-written and fairly comprehensive comparisons between the two closed-loop systems on the market. Personally, I like this one (it's a little outdated, but the comparison between Control IQ and the 670G is on point). Another good, detailed comparison between the two systems can be found here.
The Control IQ system works by automatically adjusting your basal rate (aka background insulin) up or down to keep your BGL within a fixed target range. The algorithm uses the rate of rise or fall and amount of active insulin to determine when and how much to adjust the basal rate. Where Control IQ differs from Medtronic's 670G hybrid closed-loop system is that Control IQ delivers automatic-corrections if your BGL is predicted to rise above 180 mg/dL to increase your time in-range (for the record, the next generation Medtronic system will also deliver automatic corrections). This helps reduce highs if you forget to bolus for food. It also has two activity modes that adjust the target BGL range and auto-corrections: sleep mode and exercise mode. I'll get into those in more detail in a bit, cuz I'm super impressed with exercise mode.
The other significant (and I would argue more important) difference between the 670G and Control IQ is that the Dexcom G6 does not require any external calibrations, whereas the Guardian CGM requires calibration twice a day. As always, I'm a huge fan of having as few things to enter as possible to help reduce data entry error.
In case you were wondering, Control IQ is considered more aggressive than the 670G and has a higher time-in-range for users.
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Getting Started
One of the big selling points of Tandem is that software updates can be downloaded directly to the pump, rather than requiring a hardware trade-out. If you recall, I knew Control IQ was in the works when I switched to the t:slim last year, and the easy upgrade was a huge selling point. Tandem cut a deal with the FDA that allows t:slim users to do online training on Control IQ (rather than the traditional in-person training) to unlock a code in order to download the upgrade.
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| Feel the excitement! |
One of the big selling points of Tandem is that software updates can be downloaded directly to the pump, rather than requiring a hardware trade-out. If you recall, I knew Control IQ was in the works when I switched to the t:slim last year, and the easy upgrade was a huge selling point. Tandem cut a deal with the FDA that allows t:slim users to do online training on Control IQ (rather than the traditional in-person training) to unlock a code in order to download the upgrade.
The online training is a couple hours of mostly intuitive stuff, and a detailed breakdown of how the Control IQ algorithm works. Pretty painless overall. Like my transition to the t:slim from my Medtronic pump, the system is intuitive and user-friendly. I continue to be impressed with the interface and durability of the t:slim, as well as the effectiveness of Tandem's customer support team.
By the way, you should definitely WATCH THE TRAINING VIDEOS! My sister, apparently, did not (I guess when you switch to Tandem they don't have a mechanism to force you to do the training videos before using the pump), and as we were discussing how she liked the system, many of the things she brought up were addressed in the videos. So apparently, the videos are good. Watch 'em. Tandem also offers in-person training, which I hear is also good. But, being an anti-social engineer-type, I'm all about not talking to a human if at all possible.
As you may have gathered from the previous paragraph, I recently convinced my sister to switch to the t:slim from her Medtronic pump and closed-loop system. She's been on it for two weeks-ish. When asked, she had the following comments:
- The Dexcom app is amazing (I agree)
- She likes the size of the pump (again, I agree. The t:slim is tiny and amazing)
- She doesn't like that it has to be recharged and has concerns about battery life and not being able to just replace a AA or AAA battery (I had similar concerns when I switched over, but overall have been pretty impressed and not had any issues keeping the pump charged, even in the field or while off the grid)
- The setup was easy and user-friendly
- She dislikes that you can't change the active insulin duration (see my conclusions for a bit of discussion on this)
- The belt clip/pump case is dumb. Yet again, I agree with her. It's worth noting that after my original review, I stopped using the case all together and now just shove the pump into pockets and sports bras. It's small and light enough that this works just fine.
A random aside
As a Tandem user, issues with the Dexcom CGM are now supposed to be handled through Tandem. If you call Dexcom with an issue, they'll run you through their system and then transfer you to Tandem, who will troubleshoot/replace the CGM for you. It's a bit different and I'm not sure why it's being handled that way now, but it seems to be fine. Although if you don't call Tandem directly, you spend a bunch more time working your way through the phone tree. Personally, I think this is stupid.
By the way, you should definitely WATCH THE TRAINING VIDEOS! My sister, apparently, did not (I guess when you switch to Tandem they don't have a mechanism to force you to do the training videos before using the pump), and as we were discussing how she liked the system, many of the things she brought up were addressed in the videos. So apparently, the videos are good. Watch 'em. Tandem also offers in-person training, which I hear is also good. But, being an anti-social engineer-type, I'm all about not talking to a human if at all possible.
As you may have gathered from the previous paragraph, I recently convinced my sister to switch to the t:slim from her Medtronic pump and closed-loop system. She's been on it for two weeks-ish. When asked, she had the following comments:
- The Dexcom app is amazing (I agree)
- She likes the size of the pump (again, I agree. The t:slim is tiny and amazing)
- She doesn't like that it has to be recharged and has concerns about battery life and not being able to just replace a AA or AAA battery (I had similar concerns when I switched over, but overall have been pretty impressed and not had any issues keeping the pump charged, even in the field or while off the grid)
- The setup was easy and user-friendly
- She dislikes that you can't change the active insulin duration (see my conclusions for a bit of discussion on this)
- The belt clip/pump case is dumb. Yet again, I agree with her. It's worth noting that after my original review, I stopped using the case all together and now just shove the pump into pockets and sports bras. It's small and light enough that this works just fine.
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A random aside
As a Tandem user, issues with the Dexcom CGM are now supposed to be handled through Tandem. If you call Dexcom with an issue, they'll run you through their system and then transfer you to Tandem, who will troubleshoot/replace the CGM for you. It's a bit different and I'm not sure why it's being handled that way now, but it seems to be fine. Although if you don't call Tandem directly, you spend a bunch more time working your way through the phone tree. Personally, I think this is stupid.
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Activity Mode (and why I love it)
Shocking disclosure: I'm not exactly the target demographic for a closed-loop CGM. My basal rates are good enough that I spend around 80% of time with my BGL in-range, and the spikes I do get are generally post-meal and exercise related. That said, the bane of every active diabetic's life is the struggle to control during- and post-exercise lows. Many of us pre-load carbs so that we go into exercise with an upward trend and use temporary basal rates to reduce during-exercise drops. It's not ideal, and research suggests that one of the reasons Type 1 diabetics struggle to lose weight is that we have to eat carbs (and thus calories) to prevent hypos during exercise, thus offsetting potential gains. Obviously, anything that allows me to use fewer carbs and exercise longer is a win in my book.
So. Activity mode. It comes in two flavours: sleep mode and exercise mode.
Sleep Mode
Sleep mode is intended to reduce nighttime hypos by turning off the auto-corrections and narrowing the target BGL range. You can set it so that sleep mode engages automatically at a certain time for different days of the week, which means there's one less thing to remember to do. I've found that sleep mode helps keep my BGL level while I sleep and I wake up around 110 mg/dL, which is pretty great. It also seems to help keep things more stable while I sleep if I've had a couple drinks (I have a long history of getting low during the night if I've been drinking). In short, sleep mode is 100% worth the cost of admission and it may be worth switching to Control IQ for sleep mode alone.
Shocking disclosure: I'm not exactly the target demographic for a closed-loop CGM. My basal rates are good enough that I spend around 80% of time with my BGL in-range, and the spikes I do get are generally post-meal and exercise related. That said, the bane of every active diabetic's life is the struggle to control during- and post-exercise lows. Many of us pre-load carbs so that we go into exercise with an upward trend and use temporary basal rates to reduce during-exercise drops. It's not ideal, and research suggests that one of the reasons Type 1 diabetics struggle to lose weight is that we have to eat carbs (and thus calories) to prevent hypos during exercise, thus offsetting potential gains. Obviously, anything that allows me to use fewer carbs and exercise longer is a win in my book.
So. Activity mode. It comes in two flavours: sleep mode and exercise mode.
Sleep Mode
Sleep mode is intended to reduce nighttime hypos by turning off the auto-corrections and narrowing the target BGL range. You can set it so that sleep mode engages automatically at a certain time for different days of the week, which means there's one less thing to remember to do. I've found that sleep mode helps keep my BGL level while I sleep and I wake up around 110 mg/dL, which is pretty great. It also seems to help keep things more stable while I sleep if I've had a couple drinks (I have a long history of getting low during the night if I've been drinking). In short, sleep mode is 100% worth the cost of admission and it may be worth switching to Control IQ for sleep mode alone.
Exercise Mode
I admit to being skeptical about exercise mode when I went through the Control IQ training. Of all the features, I expected exercise mode to be lacking and didn't have high (read: any) expectations of it being effective. In fact, I had to talk myself into giving it a chance because there was no way in hell it was going to work. Boy, was I (happily) wrong.
Like sleep mode, exercise mode tightens up the target range when activated. That said, I highly recommend leaving it on for a bit after you finish exercising to help mitigate the post-exercise crash. Thus far, I've had great success with eating 15 grams of carbs before starting a run and leaving exercise mode on for 30 minutes after I finish. Once again, between the target range while in exercise mode and the auto-adjustments of the Control IQ algorithm, I highly recommend the pump for activity mode alone. It's worth keeping in mind that going into exercise with minimal insulin on board (IOB) helps keep your BGL level.
I admit to being skeptical about exercise mode when I went through the Control IQ training. Of all the features, I expected exercise mode to be lacking and didn't have high (read: any) expectations of it being effective. In fact, I had to talk myself into giving it a chance because there was no way in hell it was going to work. Boy, was I (happily) wrong.
Like sleep mode, exercise mode tightens up the target range when activated. That said, I highly recommend leaving it on for a bit after you finish exercising to help mitigate the post-exercise crash. Thus far, I've had great success with eating 15 grams of carbs before starting a run and leaving exercise mode on for 30 minutes after I finish. Once again, between the target range while in exercise mode and the auto-adjustments of the Control IQ algorithm, I highly recommend the pump for activity mode alone. It's worth keeping in mind that going into exercise with minimal insulin on board (IOB) helps keep your BGL level.
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Conclusions
Things I love:
- Exercise mode is the bomb. F'reals. I love it and 100% recommend utilising it. As an active diabetic, I've been engaging it during cardio, like running or hiking, and strenuous activities (hauling pallets of sand comes to mind), but not while climbing, which doesn't seem to affect my BGL much.
- Sleep mode is also the bomb. My husband reports feeling less anxious about nighttime hypos since I switched over, too.
- The CGM reading is automatically filled in when you open the bolus screen (using Basel IQ you had to enter it manually).
- I have had a noticeable reduction in swings (both up and down) using Control IQ.
- I have an increased time in range and am loving it. That said, it's worth noting that it seems to take a few days (or more) for the algorithm to fine-tune itself for each personal profile (aka basal rates and ratios), so if you switch profiles, you'll see some variation in your BGL's before Control IQ starts being super effective. The only reason I noticed this is because I work night shift in the field and switched onto my "night shift" profile (which is literally my normal profile offset 12 hours).
- The size. I continue to love how small the t:slim x2 is (if you recall, it was one of the reasons I switched systems). I don't use a case and just shove it in pants pockets or a sports bra, which works shockingly well.
- Exercise mode is the bomb. F'reals. I love it and 100% recommend utilising it. As an active diabetic, I've been engaging it during cardio, like running or hiking, and strenuous activities (hauling pallets of sand comes to mind), but not while climbing, which doesn't seem to affect my BGL much.
- Sleep mode is also the bomb. My husband reports feeling less anxious about nighttime hypos since I switched over, too.
- The CGM reading is automatically filled in when you open the bolus screen (using Basel IQ you had to enter it manually).
- I have had a noticeable reduction in swings (both up and down) using Control IQ.
- I have an increased time in range and am loving it. That said, it's worth noting that it seems to take a few days (or more) for the algorithm to fine-tune itself for each personal profile (aka basal rates and ratios), so if you switch profiles, you'll see some variation in your BGL's before Control IQ starts being super effective. The only reason I noticed this is because I work night shift in the field and switched onto my "night shift" profile (which is literally my normal profile offset 12 hours).
- The size. I continue to love how small the t:slim x2 is (if you recall, it was one of the reasons I switched systems). I don't use a case and just shove it in pants pockets or a sports bra, which works shockingly well.
Things I don't love:
- Control IQ doesn't take into account the carbs on board in the bolus calcs. What this means in practice is if your BGL is below target and you treat with carbs, the pump recommends a reduced bolus. If you eat something else after treating the low, Control IQ will continue to recommend a reduced bolus, even though that is functionally double-correcting. The workaround is, obviously, to override the recommended bolus if you eat after treating a hypo. It would be nice if the Control IQ algorithm actually accounted for carbs on board as well as IOB (I should note that the Loop systems, aka hacks, do account for carbs on board).
- I've been having ongoing issues with losing connectivity with my Dexcom. It's weird (and annoying), since this issue only started when I started using Control IQ (wasn't an issue with Basal IQ). A quick internet search shows that I'm not the only person having connectivity issues with the Dex using Control IQ. In addition, I keep having issues with my CGM requiring manual calibrations upon startup, even though I have the code. I've talked with both Dexcom and Tandem about this, and once we get past the "it only asks for calibrations if it needs them" speech and I get them to understand that the CGM is requiring calibrations every 24 hours (barf), they've been... well, sorta helpful. It's annoying as shit and makes me kinda cranky with Dex. If we're being honest, the batch of sensors I've been having issues with may (read: definitely) have had some exposure to extreme cold that I'm starting to suspect messed with both the adhesive and the internal workings.
- You can't change the active insulin duration. When you're using Control IQ, it's set to 5 hours. For many of us, this is too long. I had to counter-act this by changing my food to insulin ratio and my correction ratio, resulting in a net increase in insulin usage. After talking with my sister, she had the same comment and also adjusted her ratios to compensate.
- Occasionally the screen turns off while you're mid-bolus. This doesn't interrupt the bolus, but you do have to unlock the screen again. After talking to a couple other t:slim users, this seems to be something we've all experienced. It's not particularly disruptive, but it is kinda annoying and enough to warrant a minor bitch-fest during the discussion.
Final Thoughts
I continue to love Tandem and their customer support team, and Control IQ is just another reason to be happy. I've found it works well (and as advertised) and is user-friendly with an improved interface. While there are a couple features that I wish were different (notably the insulin duration), there are work-arounds (changing food and correction ratios), but they result in an overall increased insulin usage.
The one feature of Control IQ that I was sure would be garbage turns out to be my absolute favourite. Activity mode is a powerful tool that should be utilised by all users. Sleep mode is an excellent way to help prevent nighttime hypos, andexercise mode actually works exercise mode has a place (see update below for revised conclusions). Honestly, it's almost worth switching to Control IQ for no other reason than to utilise activity mode.
Unfortunately, the Dexcom is the weak link in the system. I'm not sure where the issue originates, but I suspect it's something with the pump, since connectivity issues don't seem to extend to the phone app. I've been having some non-pump related issues with the Dex as well, which hopefully will get resolved. That said, the issues with the Dex are not significant enough to keep me from recommending Control IQ.
tl;dr
Control IQ is awesome and you should use it.
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Update (5/30/20)
I've revised my opinions on the effectiveness of Activity Mode as far as endurance activities (long, hard hikes and runs). Two months and 150 miles in, and I am less enamoured with it. It turns out, my 30-year-old body doesn't like to process sugars or carbs while exercising. Also, I get ultra-sensitive to insulin while running / doing aerobic exercise. Looking back, I've addressed this by carbo-loading and setting temp basel rates, going into long runs with a high blood sugar and no insulin corrections. Unfortunately, the Control IQ algorithm doesn't allow you to do this effectively, what with the auto-corrections to keep you in the target range and the inability to set temporary basal rates.
Regarding the Dexcom
I don't care what the official line is from Dexcom, something in their adhesive has changed that I (and many other T1D's on the internet) am super allergic to it. I'm officially doing the "sandwich" method, consisting of Flonase, tegaderm, insert sensor on top of tegaderm, then put a grifgrip patch on top. It's a lot of tape, but at least I don't get nasty, puss-y bubbles and rashes this way. Also, inserting the cgm through a barrier is not recommended (by Dex).
The customer service folks I've talked to at Dex (who are awesome, btw) have mentioned they've been receiving a really high volume of calls regarding reactions to the adhesive. Despite the fact that they insist nothing in their adhesive or manufacturing has changed, the evidence does not support that claim. It only takes a quick perusal of T1D forums to discover a surge in complaints about adhesive reactions starting around January.
- You can't change the active insulin duration. When you're using Control IQ, it's set to 5 hours. For many of us, this is too long. I had to counter-act this by changing my food to insulin ratio and my correction ratio, resulting in a net increase in insulin usage. After talking with my sister, she had the same comment and also adjusted her ratios to compensate.
- Occasionally the screen turns off while you're mid-bolus. This doesn't interrupt the bolus, but you do have to unlock the screen again. After talking to a couple other t:slim users, this seems to be something we've all experienced. It's not particularly disruptive, but it is kinda annoying and enough to warrant a minor bitch-fest during the discussion.
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Final Thoughts
I continue to love Tandem and their customer support team, and Control IQ is just another reason to be happy. I've found it works well (and as advertised) and is user-friendly with an improved interface. While there are a couple features that I wish were different (notably the insulin duration), there are work-arounds (changing food and correction ratios), but they result in an overall increased insulin usage.
The one feature of Control IQ that I was sure would be garbage turns out to be my absolute favourite. Activity mode is a powerful tool that should be utilised by all users. Sleep mode is an excellent way to help prevent nighttime hypos, and
Unfortunately, the Dexcom is the weak link in the system. I'm not sure where the issue originates, but I suspect it's something with the pump, since connectivity issues don't seem to extend to the phone app. I've been having some non-pump related issues with the Dex as well, which hopefully will get resolved. That said, the issues with the Dex are not significant enough to keep me from recommending Control IQ.
tl;dr
Control IQ is awesome and you should use it.
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I've revised my opinions on the effectiveness of Activity Mode as far as endurance activities (long, hard hikes and runs). Two months and 150 miles in, and I am less enamoured with it. It turns out, my 30-year-old body doesn't like to process sugars or carbs while exercising. Also, I get ultra-sensitive to insulin while running / doing aerobic exercise. Looking back, I've addressed this by carbo-loading and setting temp basel rates, going into long runs with a high blood sugar and no insulin corrections. Unfortunately, the Control IQ algorithm doesn't allow you to do this effectively, what with the auto-corrections to keep you in the target range and the inability to set temporary basal rates.
As I've upped my milage to 20-ish miles a week, I found myself constantly fighting hypos. I started messing around with my diet in an attempt to stave off the inevitable crash during long runs, joined a couple Facebook and reddit type 1 diabetic running groups, and trying different supplements and gels on the recommendations of other T1D runners. After much struggling and many hypos, I also stopped trying to make Control IQ work for runs farther than 3 miles and started turning it off so I could set a temporary basal rate.
So basically, Activity Mode works well until I'm doing prolonged aerobic activities, at which point I have better luck going manual (you do not get the auto-suspend when your CGM is trending low this way, fyi).
So basically, Activity Mode works well until I'm doing prolonged aerobic activities, at which point I have better luck going manual (you do not get the auto-suspend when your CGM is trending low this way, fyi).
Regarding the Dexcom
I don't care what the official line is from Dexcom, something in their adhesive has changed that I (and many other T1D's on the internet) am super allergic to it. I'm officially doing the "sandwich" method, consisting of Flonase, tegaderm, insert sensor on top of tegaderm, then put a grifgrip patch on top. It's a lot of tape, but at least I don't get nasty, puss-y bubbles and rashes this way. Also, inserting the cgm through a barrier is not recommended (by Dex).
The customer service folks I've talked to at Dex (who are awesome, btw) have mentioned they've been receiving a really high volume of calls regarding reactions to the adhesive. Despite the fact that they insist nothing in their adhesive or manufacturing has changed, the evidence does not support that claim. It only takes a quick perusal of T1D forums to discover a surge in complaints about adhesive reactions starting around January.
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