A Little Unscientific G4 Research

So in another thread, a number of people mentioned that the sensors they'd ordered/received starting in January of this year are lasting a significantly shorter time (typically <10 days) than the sensors received before this year (or the 7+) which often lasted 2 weeks or more. The theory is that Dexcom has recently made changes to something on the sensor to ensure it fails sooner, and someone suggested we take a little poll. Would you humor me by answering the questions below to see if there really might be something shady going on, and Dexcom has made changes without informing users?

1) First, for those of you who've worn sensors and/or used a receiver received both last year and after January, are you noticing a difference in sensor life in the most recent sensors? If you used the 7+, are you finding a difference between the 7+ and the G4?
2) Approximately how long have your latest sensors been lasting?
3) Can you specify either the expiration date of these sensors (ideally) or if you don't have that info, when you received them?
4) Reference and Lot Number, if available.
5) To see if it makes a difference, where on your body did you place the sensor(s), and do you use an adhesive tape?

6) Those of you whose sensors are lasting more than 10 days, do you have any special tricks that seem to make them last longer?

Thanks, all...This should be interesting. They make these sensors so darn expensive for just a piece of plastic and wire, and it is a little upsetting to think Dexcom might be purposely forcing us to buy them more frequently.

ETA: I have noticed that when I've kept the sensor on after dropped readings, when it does come back for a reading or two interspersed with the ???'s, those readings are quite accurate. Very different from the 7+, where when a sensor started failing the sensor didn't have as much difficulty getting readings, but those readings became highly inaccurate.

1) I was on the 7+ till January, and I could typically get at least 2 weeks, sometimes close to 3 on the 7+.
2) With these sensors I'm only getting around 7-8 days of good readings, but readings start dropping more and more frequently after a week.
3) Received in the beginning of January, expiration is 8/15/2014
4) Ref: 9500-27, Lot 5120292
5) I always wear them on my belly, and use Flexifix.

sensor i have on now,since 2/13/2014 exp 2014-07-30 use opsite flexfix transmitter since 2/2013 13 mo?

1) First, for those of you who've worn sensors received both last year and after January, are you noticing a difference in sensor life in the most recent sensors?
I began in June 2013 and have never gotten more than 10 days out of them.

2) Approximately how long have your latest sensors been lasting?
9 days

3) Can you specify either the expiration date of these sensors (ideally) or if you don't have that info, when you received them?
Expire April 2014

4) Reference and Lot Number, if available.
Don't have

5) To see if it makes a difference, where on your body did you place the sensor(s)?
Love handles

1) I never noticed a difference between my newest sensors and my older ones when using my receiver from last year. I was worried when I read those posts, though, as I got a new receiver last month (with updated software: 20.1.158) so I thought maybe they had changed the software to fail on purpose.

2) So far so good, though: my first sensor with the new receiver lasted 17 days and then a ton of ??? started coming and going.

Previous ones expired 10-30-13 Lot #5059591
New ones expire 08-13-14 Lot #5128237
All have REF STS-GL-041
and as I said, I started using the newer ones with my old receiver and never saw a difference, so I doubt (if there is a difference) it would be with the new sensors.

5) I always place them in the exact same place: just above my belly button at 2pm or 10pm (alternating between the two sides) and always use Liquid SkinTac + Hypafix Tape: http://tinyurl.com/G4adhesive

6) Mine have always lasted 2-3 weeks, I would just have to change the Hypafix tape halfway through, which is how I am able to just alternate between the same 2 sites (since after 2 weeks it's completely healed even if I left my G4 in too long and the skin got irritated).

I notice they are more prone to going ??? crazy when I take a hot shower and don't protect my G4 from it...

I really hope Dexcom didn't change anything on purpose, especially since my Dexcom Rep was the person who told me that they last way longer than 1 week and that I should just reset it!

I hope this helps. Thanks for starting this thread since I was curious as well... perhaps there is something else going on (for example the cold weather seemed to be affecting many people's new transmitters)

1. Yes I have noticed my sensors are lasting for less time than previously - I figured it was due to the summer vs winter conditions.
2. My last sensor lasted 18 days but this was the exception not the rule. Previous ones in the same lot only last 10-12 days.
3. The expiration date of the sensor is July 18, 2014 sensor was received in a shipment in September 2013.
4. Ref 9500-27 , lot # 5115306
5. thighs only
6. Opsite Flexifix every time.
I don't pay for my sensors, insurance covers it 100% without a copay, but I do feel like I have been gypped if they don't last at least 2-3 weeks.

Aside from the fact that I can't afford it, the sensors normally take a couple of days before they get really accurate and then I would have 2-3 weeks. So if this is true, the usefulness also goes to hell.

Sometimes I think life would be easier using the older insulins and generic strips, so I wouldn't have to deal with crap like this and insurance.

My latest sensor lasted only about 10 days, whereas my previous ones usually lasted a full 2 weeks. BUT they are from the same box, so I don't know why. I'm going to have to watch this a little longer before I can come down on one side or the other.

7+ sensors lasted about 2 weeks. Gen 4 sensors last about 9 days. The end-of-life symptoms are very different. The Gen 4 sensors go from perfect to dead in almost no time. I understand that Dexcom has a commercial interest in sabotaging the longevity of the sensors. Too bad that Dexcom cannot be reimbursed for the days that a sensor is working. For example, not get a penny for the first day.

belly,left or right side ref # 9500-27 lot 5115313

Yes yes yes, I see a big difference from the last shipment, we got these before Jan. My daughter usually gets close to 2 weeks with great reading…now lately it’s been a week plus maybe a day or two with ?? And missing data on the end.
Exp. date is 5/31/15
Ref 9500-27
Lot 5105224
Backs of arms with Mastisol (hole left for filament) opsiteflex over top when needed.
Seriously if they did this they’re shooting themselves in the foot. I was actually going to call but what do you say when you actually get that week just to the wire.
Good luck and keep us posted. Sad thing is do you actually think they would admit it though?
Lizabeth. Mom to McKenzie 13, Dx @ 3. Dex and Ping

Would like to add, the last Lot that DID last long was Lot 5067248. Exp 1/5/14 same ref#.

Hello all, this is an interesting discussion. My son (7 years old), has been on the Dexcom G4 since early January (2014). We are getting about 8-9 good days out of our sensors then we start getting error messages, mainly ???. We do not have insurance coverage so getting 2 weeks out of our sensors would have saved us about $2200 per year. The research I had done prior to purchasing the system indicated that many users were getting 2-3 weeks out of their sensors, so it would have been nice to get that long. To be clear: I did not purchase based on the assumption I would get that long, I was prepared for a week for each sensor (it just would have been nice...). I thought I was doing something wrong to be getting only 8-9 days so this theory that Dexcom have made changes to their sensors is making sense to me. Having said all this, we love our Dexcom (ok, I love the Dex).

Have been using the G4 since mid last summer and haven't noticed any changes. My rule is 2 weeks, perfect, 3rd week, a degradation, but still better than the Medtronic Enlite. At the moment have a record holding batch, 4 weeks, and perfect accuracy.
One question though. Are all the Dexcom sensors produced at the same location, or are they different for US, Europe, Australia/NZ?

I do wonder if Dexcom would even be able to change their G4 sensors.

The reason I say this is that the reason they always gave for not being able to get the Dexcom Studio Software to run on Windows 8 is that it would require FDA approval (which is a convenient way of passing the blame :)

That would imply that any changes they would make to the sensors would also require FDA approval. That being said, they obviously have updated the firmware on the receivers.
My new receiver has:
Software # SW10050
Software Rev
whereas my first receiver had the same software number, but revision number:
(that was the one I used until a few weeks ago)

Has anyone who has noticed a decrease (where all their previous sensors would last over 2 weeks, but suddenly this is no longer the case) had the same receiver this whole time?

Yes, I mentioned in a post that lead to this poll that they couldn't make a change to the sensors without FDA approval. So if they changed something it might have been:
*Decreasing sensor quality from the 7+ to the G4...Maybe that was the real reason they made the Ti wire thinner? Everyone questioned that, since it wasn't like the wires were in any way uncomfortable before the change.
*Weaker sensors were created, tested and reported to the FDA without it being publicized (is this possible?)
*Something even more shady is going on, with changes not being reported. Unlikely yes, but I've done QA for medical device companies, and they're not as regulated as all of us would like to believe, much less so than pharmaceuticals. I'm not big on conspiracy theories, but can you imagine how much uproar there would be if we learned Dexcom had done studies/reported on a weaker sensor, which they charged the same for? So they'd have every reason to keep it a secret.

Or...maybe (hopefully) it's just a few bad batches, since it seems not everybody is having the problem, in which case things could improve in time.

I have to believe there's some reason some of us are failing so much sooner than others, and sooner than we were on the 7+. Maybe the new sensors are more sensitive to weather like you suggested? Do those with longer lasting sensors live in warmer climates? (I'm in the Northeast.) I wish we could figure out what it is you lucky people are doing so that the rest of us could duplicate it!

This is interesting to contemplate. My last sensor only went 9 days and yet the one before from the same batch same lot lasted 18 days. I live in the Northeast. I just opened up a new box from my most recent shipment of 12. I'll just have to see how it goes. But I am already embroiled in the whole Freestyle strip/Omnipod PDM debaucle I just can't stand the thought that another one of the companies I rely on to live a healthy life with D is doing something shady behind the scenes.

Actually if you feel bad that the sensors are so expensive, I think they are the best value of all 3 components (sensor, transmitter, and receiver). The sensor has a platinum filament, several layers deposited on it (oxidation electrode, permeable membrane, enzyme layer) and a silver reference electrode. They are high tech.

Can't say the same for the (here in NZ) $900 transmitter which we have to replace after 6 months since can't change the battery. That has about $30 of kit in it. The receiver costs as much as a high-end smartphone without much in the way of smarts.

I'm not affiliated in any way with Dexcom, my son uses it, and it's like being given the gift of sight after wandering blind in the wilderness.

My second sensor using my new receiver is having similar issues (but before the 2 week mark this time).

All was fine until day 12, when ??? showed up 1 hour after taking a hot shower.
It finally came back to life and was fine until the next day after I took another hot shower... and every day since then it happens after I shower.

I chose to stick with it on day 14, I've popped the transmitter out to dry it after showering. I'm now on day 15 and it gave me ??? for the past 30 minutes (after showering 1.5 hours ago and cleaning the transmitter and sensor with a Q-tip afterwards) but now my G4 has come back and working fine.

I expect that it'll be all good until I shower tomorrow... does Dexcom not want me to shower? ;-)

What is odd is that it is super accurate when it revives itself (someone else had mentioned this as well) so maybe the new receiver software update ( is just more strict about what the G4 will report?
ie if it feels that something is off (such as a hot shower affecting readings, in my case) it will just revert to ??? rather than return a value that it knows is wrong?
Because for the remaining 23 hours of the day, it's as accurate as ever... but it's super-stressful waiting to see if it will come back from the ??? or not.

My next test will be to revert back to my older receiver when this sensor dies for good (using this same batch of sensors) to see if the receiver software update is the difference.

How do you get so many days out of your sensors? I usually change mine after 7 days because they are about to fall off. I have had skin issues with my minimed too (and omnipod before that). I just started using the dexcom in dec so I don’t really have info for your survey.