Dexcom G6 Review

This began as a G5 review, but the application infuriates me so that I’m unable to put a coherent post together. After about half a year, Medicare has finally approved coverage for the G6. And it is apparently so much more accurate that not only do you not have to enter in blood sugars to calibrate it, they’ve stopped covering test strips to do that with. After a few days of use it becomes extremely clear that it isn’t that much more accurate, and the app still asks for calibration readings, but you’ve got to pay for the test strips out of pocket to use this device now, so that’s lovely. I need this post to respond to their response to my iTunes review I know they’ll leave… which will end in a form with a 120 character limit for me to explain these issues and a schedule they’ll – in turn – blatantly disregard when they “try” to get into touch with me.

Displaying this all the time doesn’t absolve you of your responsibility for making a device/app combo that works. Show this maybe once on install… and never again, please.

I’ll mention the device they provide with the sensor and transmitter only to point out that it is virtually unusable. It is slightly smaller than an iPhone, is a touch screen with the exception of a mysterious “home” button… but has no memory, you can’t see more than an hour window of blood sugars, can’t even hover the points like you can in the iPhone app… and it doesn’t allow the data to be shared with anything… including the iPhone app… making it about the most worthless device ever. But if that isn’t enough features for you: the battery has a tremendously short life span as well.

This leaves you with the only option of using the iPhone/Android application. I will assume that problems persist across platform and describe the iPhone experience: this is quite possibly the worst designed application for a phone. True of the G5… and every awful part of that application has had the volume turned up to 11 for the G6. Unlike other applications on the iPhone which can re-enable themselves at certain times or when in proximity to certain devices… this application ceases to function entirely if you’ve closed it – with notable annoying exceptions: if you have used up all of your sensors and can’t install another one, for instance: even when closed it can bypass the phone’s “do not disturb” feature and beep at 100% volume at 2am to let you know that it’s not receiving data.

Which brings up alerts: their behavior is inconsistent and irritating, fix it. I have the mute switch on my phone flipped, I assume this does make a difference, but I can only assume it would be worse if I were to switch sounds “on”. There is a random alert that will trigger for each event, be it a high sugar, low sugar or something device specific like “signal loss”. What I would expect is a normal phone vibration as if I have an incoming call. If I do not interact with the app, maybe an audible alert happens at 50% volume or something, maybe tries another at 75% volume if I haven’t responded in a few minutes. But what actually happens appears to be a completely random selection of any of the above mentioned alert styles OR a 100% volume repetitive “get an ambulance immediately” style alert. I am just as likely to get any of the alerts for any condition… it screaming like I’m about to die when I reach my custom set alert of 230… and a soft soothing vibrating nudge when I’ve reached the critical low limit of the meter at which it ceases to even produce a numeric value.

I’m sure someone is really proud of their work on the predictive algorithm they’ve worked on, and chances are someone else is really proud of how the calibration system blatantly disregards any user-entered data points that conflicts with any calculations it has come up with for a three hour period or so, but the combination of these two things make for a delusional device that just throws tantrums if you try to correct it.

It’s obvious this device has both a hidden data set and a hidden clock it does not share with the user, that needs to go, immediately. It is severely crippling any potential accuracy this device has and that is particularly noticeable when attempting “calibration” – which is a term you need to redefine for the use of this device. Firstly, please return the calibration button back to the main screen, as it is clear it will be needed a LOT to keep this unit from going insane. Second: allow it to actually function. And by that I mean: when I enter a blood test value from a meter where it is documented that 95% of tests are within +/- 10 units of lab results, you don’t argue with me! When I enter a value, that display better respond in the affirmative and display that value. If you’re doing math, which you obviously are: you’re doing something wrong.

It’s obvious that what’s been done here is some algorithm has been found to make the graph look pretty. This doesn’t make it more accurate. It could… but only if you disregard your would-be future trend when one or more calibration results show you to be in error: The display shows 275 with two up arrows… I test and find my sugar is 195 and input that into calibration… within 20 minutes it says it’s 275 again (with 2 up arrows). I test my sugar and find it’s 192, and so input that. 20 minutes later, the display AGAIN says I’m 275 (with 2 up arrows). I test again and it’s 154. When I put in my sugar this time I get the screen of death for this device which may well persist well past the time I have given up and gone to sleep, where it continues to gripe about a calibration error and refuses to accept any value given, every 15 minutes until you eventually stop trying. It has the same behavior with low sugars, it just depends on what “mood” the device is in to tell you what your sugar is: accurate values, high values or low values. I am absolutely confident that you’ve set it on a non stop track with whatever draws the more consistent looking graph, as you have it blatantly denying every data point given to it. Once two calibration readings were given to the device, the arrows on the display should have updated if NOTHING else. If it can’t determine the difference between two manually entered values, all it’s doing is drawing.

I recommend putting the “Share” button under the “Settings” section as it is unlikely to be used by anyone more than once after installing the application… other than by accidentally pressing it. If a child, you’d have your parent click this to set up their phone on it… if you are not… well you probably won’t have a use for this icon ever, as there’s an altogether different procedure for sharing data with your doctor. And you can’t use it yourself since the go-with display device for the Dexcom… cannot follow the app, nor share data with the app. I do recommend putting the calibrate button back on the main screen given as it’s still very much necessary to get the meter back on track when it goes crazy.

Please make both alerts and calibration requests be not stupid. If I just entered in a calibration value of 240, I do not need my phone to sound off like I’m about to die any minute five minutes later… I already KNOW what my blood sugar is – I told the app that – and it’s generally not even showing the value I put; so I know better than it does: I do not need an alert. I really think there shouldn’t be any alerts within 15-maybe 20 minutes of interacting with the app. What there should NEVER be… is a reminder to calibrate within 20 minutes of my having done so. I can’t tell you how many times I’ve gotten pinged to do a calibration 5 minutes after having given it a number… please also reveal the clock so that I know when to enter it to keep the machine happy as well as accept results provided in a window of time – just set that up in such a way that an alert or reminder will not be sent to the user within x minutes of having entered a value, because that’s just irritating.

Do not “cherry pick” the calibration values. I know it only bothers “counting” every 3rd or 4th entry. It effectively ignores any calibration “too early” for it, and consistently asks for a new one mere minutes after a reading was just entered. Between that and the only way to update the number on the display is to calibrate twice consecutively: so you know it has ignored at least one of those. Every data point should be being used and not be being ignored. I strongly believe you will improve accuracy by a solid 50% by using the patient’s data. Our meters will always be better than yours. Sorry but, deep down you know that none of our meters have ever been affected in any way by Tylenol.

I notice the application also no longer displays the sensor’s serial number anywhere. Still shows the transmitters serial, may be helpful to have that information at hand too.

The graph line with readings: when I hover over points it gives me the date and time the test was taken. When this was the G5 app, IT ALSO GAVE THE READING. Why would you remove that????

I am sorry this was long, I hope some of it is helpful. I use this device because I have to have it. I cannot sense when my sugar is low anymore. I would strongly discourage anyone would use this device in conjunction with an insulin pump as its internal programming causes it to behave like a stubborn petulant imbecile. There is virtually no chance it won’t over or underdose you within a day or two.

Wouldn’t be so bad if EVERYTHING wasn’t a lie: there’s no blue-tooth device in the world that takes 3 hours to do anything. Even the “warm up” is a lie, the unit is as warm as it’s ever going to get 20 minutes in, I’m certain. If anything, they’ve determined that readings are more accurate 3 hours in… but you could just say that. As you’ve led with a lie, everything else you say must also be called to question.


After having this new device a while longer I’ve been able to make additional observations about its “calibration” behavior: again, this is a poor word to use for this feature as INSTEAD of calibrating, it has already predetermined itself to be infallible. Any deviation between the reading I provide it and the reading it is currently showing on the display it assumes to be the amount of change it has detected between the last blood sugar it registered and the one I’ve just manually taken. As a result, every “calibration” entered, if it doesn’t match the blood sugar already showing on the display… just increases the sensitivity to every tiny fluctuation in blood sugar until the readings are so far from actual as to be dangerous to use for anything. I would therefor not recommend “calibrating” – ever, if it is avoidable, as this just makes the thing more and more inaccurate. You have to just accept and live with the readings being 20-40 points off for virtually every reading. Trying to give it accurate information just makes it worthless and irritating since after doing that a few times… the tiniest fluctuation down makes it think your blood sugar is about to fall off its readable scale and the tiniest fluctuation up makes it think your blood sugar is about to land you in the hospital or be virtually incapable of moving with a 500+ blood sugar… where as in reality your sugar is just dancing around between 90 and 150.