Dexcom G6: new phone and new sensor

In the previous posts on the Dexcom G6, I’ve talked about the setup flow and the review after a week, before the first sensor expired. This was intentional because I wanted to talk about the sensor replacement flow separately. Turns out this post will also have a second topic to it, which came by by chance: how do you reconfigure the app when you change phone or, like it happened to me this time, when you are forced to do a factory reset.

I won’t go into the details of why I had to do a factory reset. I’ll just say that the previous point about email and identities was involved.

So what happens when the Dexcom is installed on a new phone, or when you have to reinstall this? The first thing it will ask you is to login again, which is the easy part. After that, though, it will ask you to scan the sensor code. Which made no sense to me! I said “No Code”, and then it asked me to scan the transmitter code. At which point it managed to pair with the transmitter, and it showed me the blood sugar readings for the past three hours. I can assume this is the amount of caching the transmitter can do. If the data is at all uploaded to Dexcom system, it is not shown back to the user beside those three hours.

It’s important to note here that unless you are at home (and you kept the box the transmitter came with), or you have written down the transmitter serial number somewhere, you won’t be able to reconnect. You need the transmitter serial number for the two of them to pair. To compare again this to the LibreLink app, that one only requires you to log in with your account, and the current sensor can just be scanned normally. Calibration info is kept online and transmitted back as needed.

A few hours later, the first sensor (not the transmitter) finally expired and I prepared myself to set the new one up. The first thing you see when you open the app after the sensor expired is a “Start new Sensor” button. If you click that, you are asked for the code of the sensor, with a drawing of the applicator that has the code printed on the cover of the glue pad. If you type in the code, the app will think that you already set up the whole sensor and it’s ready to start, and will initiate the countdown of the warm up. At no point the app direct you to apply the new sensor. It gives you the impression you need to first scan the code and then apply the sensor, which is wrong!

Luckily despite this mistake, I was able to tell the app to stop the sensor by telling it I’d be replacing transmitter. And then re-enrolling the already present transmitter. This is all completely messed up in the flow, particularly because when you do the transmitter re-enrolment, the steps are in the correct order: scan then tell you to put the transmitter in, and then scan the transmitter serial number (again, remember to keep the box). It even optionally shows you the explanation video again — once again, totally unlike just starting a new sensor.

To say that this is badly thought out is an understatement to me. I’ll compare this again with the LibreLink app that, once the sensor terminates, actually shows you the steps to put on a new sensor (you can ignore them and go straight to scanning the sensor if you know what you’re doing).

On the more practical side, the skin adhesive that I talked about last week actually seems to work fine to keep the sensor in place better, and it makes dealing with my hairy belly simpler by bunching up the hair and keep it attached to the skin, rather than having it act as a fur against the sensor’s glue. It would probably be quite simpler to put on if they provided a simpler guide on the size of the sensor though: showing it on the video is not particularly nice.

The sensor still needed calibration: the readings were off by more than 20% at first, although they are now back on track. This either means the calibration is off in general, or somehow there’s a significant variation between the value read by the Dexcom sensor and the actual blood sugar. I don’t have enough of a medical background to be able to tell this, so I leave that to the professionals.

At this point, my impression of the Dexcom G6 system is that it’s a fairly decent technical implementation of the hardware, but a complete mess on the software and human side. The former, I’m told can be obviated by using a third-party app (by the folks who are not waiting), which I will eventually try at this point for the sake of reviewing it. The latter, probably would require them to pay more attention to their competitors.

Abbott seems to have the upper-hand with the user-friendly apps and reports, even though there are bugs and their updates are very far in between. They also don’t do alerts, and despite a few third-party “adapters” to transform the Libre “flash” system into a more proper CGM, I don’t think there will be much in the form of reliable alerts until Abbott changes direction.

Dexcom G6: week 1 review

Content warning, of sorts. I’m going to talk about my experience with the continuous glucose monitor I’m trying out. This will include some PG-rated body part descriptions, so if that makes you awkward to read, consider skipping this post.

It has now been a week since I started testing out the Dexcom G6 CGM. And I have a number of opinions, some of which echo what I heard from another friend using the Dexcom before, and some that confirmed the suggestion of another friend a few years back. So let me share some of it.

The first thing we should talk about is the sensor, positioning and stickiness. As I said in the previous post, their provided options for the sensor positioning are not particularly friendly. I ended up inserting it on my left side, just below the belly button, away from where I usually would inject insulin. It did not hurt at all, and it’s not particularly in the way.

Unfortunately, I’m fairly hairy and that means that the sensor has trouble sticking by itself. And because of that, it becomes a problem when taking showers, as the top side of the adhesive strip tends to detach, and I had to stick it with bandage tape. This is not a particular problem with the Libre, because my upper back arm is much less hairy and even though it can hurt a bit to take it off, it does not hurt that much.

As of today, the sensor is still in, seventh day out of ten, although it feels very precarious right now. During one of the many videos provided during the original setup, they suggest that, to makes it more stable to stick, I should be using skin adhesive. I had no idea what that was, and it was only illustrated as a drawing of a bottle. I asked my local pharmacy, and they were just as confused. Looking up on their supplier’s catalogue, they found something they could special order, and which I picked up today. It turns out to be a German skin adhesive for £15, which is designed for urinary sheaths. Be careful if you want to open the page, it has some very graphical imagery. As far as I can tell, it should be safe to use for this use case, but you would expect that Dexcom would at least provide some better adhesive themselves, or at least a sample in their introductory kit.

I will also have to point out that the bulge caused by the sensor is significantly more noticeable than the Libre, particularly if you have tight-fitting shirts, like I often do in the summer. Glad I listened to the colleague who thought it would look strange on me, back a few years ago.

Let’s now talk about the app, which I already said before was a mess to find on the store. The app itself looks bare bones — not just for the choice of few, light colours (compare to the vivid colours of LibreLink), but also due to the lack of content altogether: you get a dial that is meant to show you the current reading, as well as the direction of the reading between “up fast” and “down fast”, then a yellow-grey-red graph of the last three hours. You can rotate the phone (or expect the app to read it as a rotation despite you keeping your phone upright) to see the last 24 hours. I have not found any way to show you anything but that.

The app does have support for “sharing/following”, and it does ask you if you want to consent to data sharing. Supposedly there’s an online diabetes management site — but I have not found any link of where that is from the app. I’ll probably look that up for another post.

You’ll probably be wondering why I’m not including screenshots like I did when I reviewed the Counter Next One. The answer is that the app prevents screenshots, which means you either share your data via their own apps, or you don’t at all. Or you end up with taking a picture of one phone with another one, which I could have, but I seriously couldn’t be bothered.

The Settings menu is the only interaction you can actually spend time on, with the app. It’s an extremely rudimentary page with a list of items name-value pairs effectively. Nothing tells you which rows are clickable and which ones aren’t. There’s a second page for Alerts, and then a few more Alerts have their own settings page.

Before I move onto talking (ranting?) about alerts, let me take a moment to talk about the sensors’ lifetime display. The LibreLink app has one of the easiest-to-the-eyes implementation of the lifetime countdown. It shows as a progress bar of days once you start the sensor, and once you reach the last day, it switches to show you the progress bar for the hours. This is very well implemented and deals well with both timezone changes (I still travel quite a bit) and daylight savings time. The Dexcom G6 app shows you the time the sensor will end with no indication of which timezone is taken in.

The main feature of a CGM like this, that pushes data, rather than being polled like the Libre, is the ability to warn you of conditions that would be dangerous, like highs and lows. This is very useful particularly if you have a history of lows and you got desensitised to them. That’s not usually my problem, but I have had a few times where I got surprised by a low because I was too focused on a task, so I was actually hoping it would help me. But it might not quite be there.

First of all, you only get three thresholds: Urgent Low, Low and High. The first one cannot be changed at all:

The Urgent Low Alarm notification level and repeat setting cannot be changed or turned off. Only the sound setting can be changed.

The settings are locked at 3.1mmol/L and 30 minutes repeat, which would be fairly acceptable. Except it’s more like 10 minutes instead of 30, which is extremely annoying when you actually do get an urgent low, and you’re trying to deal with it. Particularly in the middle of the night. My best guess of why the repeat is not working is that any reading that goes up or stays stable resets the counter of warning, so a (3.1, 3.2, 3.1) timeseries would cause two alerts 10 minutes apart.

The Low/High thresholds are used both for the graph and for the alert. If you can’t see anything wrong with this, you never had a doctor tell you to stay a little higher rather than a little lower on your blood glucose. I know, though, I’m not alone with this. In my “usual” configuration, I would consider anything below 5 as “out of range”, because I shouldn’t linger at that value too long. But I don’t want a “low” alert at that value, I would rather have an alert if I stayed at that value for over 20 minutes.

I ended up disabling the High alert, because it was too noisy even with my usual value of 12 ­— particularly for the same reason noted above about the timeseries problem: even when I take some fast insulin to bring the value down, there will be another alert in ten minutes because the value is volatile enough. It might sounds perfectly reasonable to anyone who has not been working with monitoring and alerting for years, but to me, that sounds like a pretty bad monitoring system.

You can tweak the alerts a little bit for overnight alerts, but you can’t turn them off entirely. Urgent Low will stay on, and that has woken me up a few nights already. Turns out I have had multiple cases of overnight mild lows (around 3.2 mmol/L), that recover themselves without me waking up. Is this good? Bad? I’m not entirely sure. I remember they used to be more pronounced years ago, and that’s why my doctor suggested me to run a little higher. The problem with those lows, is that if you try too hard to recover from them quickly, you end up with scary highs (20mmol/L and more!) in the morning. And since there’s no “I know, I just got food”, or “I know, I just got insulin” to shut up the alerts for an hour or half, you end up very frustrated at the end of the day.

There is a setting that turns on the feature called “Quick Glance”, which is a persistent notification showing you the current glucose level, and one (or two) arrows determining the trend. It also comes with a Dexcom icon, maybe out of necessity (Android apps are not my speciality), which is fairly confusing because the Dexcom logo is the same as the dial that shows the trend in the app, even though in this notification it does not move. And, most importantly, it stays green as the logo even when the reading is out of range. This is extremely annoying, as the “quick glance” to the colour, while you’re half asleep, would give you the totally wrong impression. On the bright side, the notification also has an expanded view that shows you the same 3 hours graph as the app itself would, so you rarely if ever see the app.

Finally, speaking of the app, let me bring up the fact that it appears to use an outrageous amount of memory. Since I started using the Dexcom, I end restarting Pokémon Go every time I switch between it and WhatsApp and Viber, on a Samsung S8 phone that should have enough RAM to run all of this in the background. This is fairly annoying, although not a deal breaker for me. But I wouldn’t be surprised if someone using a lower-end phone would have a problem trying to use this, and would have to pay the extra £290 (excluding VAT) for the receiver (by comparison, the Libre reader, which doubles as a standard glucometer – including support for β-ketone sticks – costs £58 including VAT).

Since I just had to look up the price of the reader, I also have paid a little more attention to the brochure they sent me when I signed up to be contacted. One of the thing it says is:

Customize alerts to the way you live your life (day vs night, week vs weekend).

The “customization” is a single schedule option, which I set up for night, as otherwise I would rarely be able to sleep without it waking me up every other night. That means you definitely cannot customize them the way you live your life. For instance, there’s nothing to help you use this meter while going to the movies: there’s no way to silence the alerts for any amount of time (some alerts are explicitly written so that Android’s Do Not Disturb do not block them!), there’s no silent-warning option, which would have been awesome together with the watch support (feel the buzz, check the watch, see a low—drink the soda, see a high—get the insulin/tablet).

A final word I will spend on the calibration. I was aware of the Dexcom at its previous generation (G5) required calibration during setup. As noted last week, this version (G6) does not require that. On the other hand, you can type in a calibration value, which I ended up doing for this particular sensor, as I was worried about the >20mmol/L readings it was showing me. Turns out they were not completely outlandish, but they were over 20% off. A fingerstick later, and a bit of calibration, seem to be enough for it to report a more in-line value.

Will I stick to the Dexcom G6 over the Libre? I seriously doubt so by now. It does not appear to match my usage patterns, it seems to be built for a different target audience, and it lacks any of the useful information and graphs that the LibreLink app provides. It also is more expensive and less nice to wear. Expect at least one more rant if I can figure out how to access my own readings on their webapp.

Testing the Dexcom G6 CGM: Setup

I have written many times before how I have been using the FreeStyle Libre “flash” glucose monitor, and have been vastly happy with it. Unfortunately in the last year or so, Abbott has had trouble with manufacturing capacity for the sensors, and it’s becoming annoying to procure them. Once already they delayed my order to the point that I spent a week going back to finger-pricking meters, and it looked like I might have to repeat that when, earlier in January, they notified that my order would be delayed.

This time, I decided to at least look into the alternatives — and as you can guess from the title, I have ordered a Dexcom G6 system, which is an actual continuous monitor, rather than a flash system like the Libre. For those who have not looked into this before (or who, lucky them, don’t suffer from diabetes and thus don’t spend time looking like this), the main difference between these two is that the Libre needs to be scanned regularly, while the G6 sends the data continuously from the transmitter to a receiver of some kind.

I say “of some kind” because, like the Libre, and unlike the generation I looked at before, the G6 can be connected to a compatible smartphone instead of a dedicated receiver. Indeed, the receiver is a costly optional here, considering that already the starter kit is £159 (plus VAT, which I’m exempt from because I’m diabetic).

Speaking of costs, Dexcom takes a different approach to ordering than the Libre: it’s overly expensive if you “pay as you go”, the way Abbott does it. Instead if you don’t want to be charged through the nose, you need to accept a one year contract, for £159/month. It’s an okay price, barely more expensive than the equivalent Abbott sensors price, but it’s definitely a bit more “scary” as an option. In particular if you don’t feel sure about the comfort of the sensor, for instance.

I’m typing this post as I opened the boxes that arrived to me with the sensor, transmitter and instructions. And the first thing I will complain about is that the instructions tell me to “Set Up App”, and give me the name of the app and its icon, but provides no QR code or short link to it. So I looked at their own FAQ, they only provide the name of the app:

The Dexcom G6 app has to be downloaded and is different from the Dexcom G5 Mobile app. (Please note: The G6 system will not work with the G5 Mobile app.) It is available for free from the Apple App or Google Play stores. The app is named “Dexcom G6”

Once I actually find the app, that is reported as being developed by Dexcom, I actually find Dexcom G6 mmol/L DXCM1. What on Earth, folks? Yes of course the mmol/l is there because it’s the UK edition (the Italian edition would be mg/dl), and DXCM1 is probably… something. But this is one of the worst way to dealing with region-restricted apps.

Second problem: the login flow uses an in-app browser, as it’s clear from the cookies popup (that is annoying on their normal website too). Worse, it does not work with 1Password auto-fill! Luckily they don’t disable paste at least.

After logging in, the app forces you to watch a series of introductory videos, otherwise you don’t get to continue the setup at all. I would hope that this is only a requirement for the first time you use the app, but I somewhat don’t expect it to be as good. The videos are a bit repetitive, but I suppose they are designed to help people who are not used to this type of technology. I think it’s of note that some of the videos are vertical, while other are horizontal, forcing you to move your phone quite a few times.

I find it ironic that the videos suggests you to keep using a fingerstick meter to take treatment decisions. The Libre reader device doubles as a fingerstick meter, while Dexcom does not appear to even market one to begin with.

I have to say I’m not particularly impressed by the process, let alone the opportunities. The video effectively tells you you shouldn’t be doing anything at all with your body, as you need to place it definitely on your belly, but away from injection sites, from where you could have a seatbelt, or from where you may roll over while asleep. But I’ll go with it for now. Also, unlike the Libre, the sensors don’t come with the usual alcohol wipes, despite them suggesting you to use it and have it ready.

As I type this, I just finished the (mostly painless, in the sense of physical pain) process to install the sensor and transmitter. The app is now supposedly connecting with the (BLE) transmitter. The screen tells me:

Keep smart device within 6 meters of transmitter. Pairing may take up to 30 minutes.

It took a good five minutes to pair. And only after it paired, the sensor can be started, which takes two hours (compare to the 1 hour of the Libre). Funnily enough, Android SmartLock asked if I wanted to use to keep my phone unlocked, too.

Before I end this first post, I should mention that there is also a WearOS companion app — which my smartwatch asked if I wanted to install after I installed the phone app. I would love to say that this is great, but it’s implemented as a watch face! Which makes it very annoying if you actually like your watch face and would rather just have an app that allowed you to check your blood sugar without taking out your phone during a meeting, or a date.

Anyhoo, I’ll post more about my experience as I get further into using this. The starter kit is a 30 days kit, so I’ll probably be blogging more during February while this is in, and then finally decide what to do later in the year. I now have supplies for the Libre for over three months, so if I switch, that’ll probably happen some time in June.