Continuous glucose monitors or CGMs have earned an essential place in the treatment options to those of us that must run our glucose metabolism on “manual.” CGMs, however, are not 100% dependable.
Some fail at the outset when inserted in a particularly painful location. Some sensors fail early or produce unreliable data or a stream of false lows or highs along with nagging alarms.
Now, I know that success with CGMs sensor consistency and durability varies from manufacturing lots and between various people with diabetes. I know I had much better CGM performance when I was younger.
One thing I’ve done with insulin infusion sets is to request that the Rx ordering doctor specify to change the infusion set every 2 days instead of the usual 3 days. This restores the power to the diabetic and eliminates the worry of running out of supply.
To keep the on-hand supply from growing excessive, the person with diabetes can simply forgo a 90-day supply order from time to time.
I’m wondering if anyone here has been successful using this tactic with CGMs? Just because the manufacturer claims that the sensor should last 10 days definitely does not mean it actually lasts 10 days!
Insurers play a role, too.
Has anyone here been successful with their doctor’s order specifying changing the CGM before the manufacturer’s expected sensor lifespan?
With Dexcom expected to increase their expected sensor lifespan from 10 to 15 days, this situation could get worse for at least some of us.
I made an account so I can test communications between the pharmacists and the 'betics. Might take a few days to get access. I gave them $20. Maybe they want $100 to access the forum. I’m not giving them that until I see them out lobbying on the Hill.
In my experience, Dexcom has been very good about replacing failed sensors. And replacement gives a few addiitonal days insurance doesn’t know about. So starting a fight with insurance shouldn’t be necessary. If a crappy medical supplier is also part of the mix, then I don’t know …
Yeah, but the burden of calling them for every sensor failure (if he’s getting a lot of them) is gonna be untenable. They have to overwrite the allotted amount on the script.
Thanks for the comment, William. It reminds me that my experience is not the mainstream.
For many years my Dexcom sensors lasted longer than advertised. Unfortunately, the G7 shut off the possibility of extending dependable wear-time with the added bonus of easing access worries.
Combined with that trend, I personally experienced a problem with G6 sensors not lasting a full 10 days. (Aging skin, body composition? Deliberate sensor longevity downgrading by Dexcom engineering?)
When I reported these early failures, I was told by Dexcom reps that replacements were now limited to 3 sensors per year. I have now decided not to report sensors that fail after 7 days. That has put a serious dent in my supply “comfort stock.” Again, I realize that my personal experience is not mainstream.
I still get the replacements of 3 failed sensors per year, but no more. Now I know that I could argue with the Dexcom reps for more replacements but that activity has its own “costs.”
Going forward, I’ve delayed switching to the G7 since I worry that I will not find consistent full 10-day success, much less 15 days that is now being talked about. The major change in the G7 design is the adoption of 90 degree sensor filament as compared to the Dexcom classic (G6 and before) angled sensor placement. I hope my worries are unfounded but I’ve read enough stories regarding unsatisfied users. We’ll see – I know the G6 production line will be shut down in the not-too-distant future.
Yeah, I got admonished about the 3/yr limit last time I had one fail prematurely, too. I seem to recall it used to be 3/month, if you were really unlucky or pushing your luck.
But back to the original question, I’m curious whether anyone has tried this. That ten-day session thing seems much more hardwired than the 3-day standard for insets. I actually had my supplier suggest changing my inset prescription to 2-day when I had a string of bad ones. But my Dexcom supplier is assiduous about keeping count of my time since last script was filled and only doing a reorder when I’m down to ten days left (last sensor session). So I’d be surprised if your doc could affect this but I’d be happy to be proved wrong.
I currently have a 90-day back-up supply, built up by doing a few extended sessions and maybe having a couple “bad” ones I managed to live out the whole session with (as when I’ve asked for a replacement due to a painful insertion, which can happen). Of course all this is going to be moot when they finally kick me off the G6 but my plan is to hang on until that point, as the user reviews continue to be pretty mixed on the G7.
Just want to say that I really like the
G7. Once in a while I have a problem, but they always go the 10 days for me. I am somewhat concerned about the G7 shortages. I just received my US Med order and there were only 3 sensors. Luckily I have several extras. Hopefully the shortage problem will be solved quickly.
L33822
For delivery of refills, the supplier must deliver the DMEPOS product no sooner than 10 calendar days prior to the expected end of the current supply.
DME suppliers are audited by medicare and if the supplier is caught not abiding by the rules Medicare takes the money it paid for the sensors back.
I’m with @Terry4 and delaying changing to the G6 due to angle change. I was using the original Libre before the G6 and based on my experience think the angle of the G6 improves its reliability. It’ll be interesting to compare the G7 when I have to. Personally I don’t give the mixed reports much weight. People rarely report when things work.
To state the obvious, the suppliers make money by sending you stuff and having your insurance pay for it. They’d send you a new sensor every day if they’d get reimbursed for it. Insurers don’t want to pay for anything beyond what is needed.
Also, my understanding was that the 3 replacements/year Dexcom policy refers to replacements issued without “proof”. If you can send back a faulty sensor and its inserter, they will replace and examine it. But something subjective like pain on insertion or insufficient accuracy by your standards (not theirs) would count against the three as would sensors that lasted a significant part of but not all the 10 days. Not 100% certain about the policy, but I needed a replacement for one where I’d thrown out both the inserter and the sensor after they failed and I understood that if I’d kept the inserter and sensor and had been able to send them back that wouldn’t have counted against my 3/year.
You’re likely correct. I just recall them being a lot more easy-going back before the CGM space started being so competitive. I remember mentioning the pain issue in a support call about something else, and the agent saying “Oh, you should call us when that happens and we’ll replace it–we don’t want you in pain!” Just a much more personal vibe from Dexcom back then.
This triggered another thought in me. Sensors sometimes fail with a message along the lines of “sensor failed and session is now ended, no more alerts and alarms, replace sensor now.” I believe that customer service reps can see these failures on their end and likely think of this as a “hard failure.”
I’ve also observed that my efforts to calibrate and salvage the session when it is acting poorly will often precipitate this hard failure. Instead of me pulling the plug on a badly acting sensor, I could humor the situation with dire attempts (slightly > than 30 mg/dL) to recalibrate and trip the sensor into killing itself with a hard failure.
I’m not trying to gain an unfair advantage here. I just want Dexcom to stand behind their warranty that every sensor will last 10 days while maintaining reasonable accuracy.
Medicare constructs their fiduciary policies based on this fact. I definitely think it’s unreasonable to expect the supply firms to deliver sensors 100% of the time on a 10 day notice. In the meantime, the safety and health of the CGM sensor users hangs in the balance!
This could be the more pragmatic path to take rather than making a request for my doctor to order < 10 days wear time and hope that Medicare will cooperate.
He had tried an experiment wearing both G6 and G7 sensors and tracking his overall BG management with each. He found G7 sometimes, but regularly, reported false BG levels – sometimes incorrectly higher than the actual level and sometimes lower – causing him to take incorrect action. Bottom line – he concluded G7 resulted is poorer BG management than G6. He guessed Dexcom wanted to be able to advertise their product was more accurate than the competition, causing them to change their G6 data smoothing algorithm.
While only one tester and one data ponit, I decided to wait to switch to G7. And I am one of those who can successfully restart a G6 sensor, normally getting 20 accurate days from each sensor. But I have read many posts here by plenty of others whose sensors stop being accurate before the expected number of days. Each body is different. and TuDiabetes Forum is proof of that. Working with your doctor, it looks like you have found a workable solution.
… In my case, I also found an online pharmacy in Canada selling G6 transmitters for quite an affordable price. So I have built up a decent surplus of G6 sensors and transmitters. The reason – I live in fire and earthquake country, and I feel better knowing if there is a supply disruption, at least I have a CGM inventory.
Of course, I will have to convert to G7 at some point, and I doubt those will ever get hacked in a reasonable way to allow restarts. So once I switch, I will continue using my G6 inventory and build up a G7 inventory. Note I am not reselling my surplus or otherwise trying to cheat Dexcom – I expect to use every sensor and they are getting paid for them. I simply have a fallback inventory if that is ever needed.
My insurance (US Medicare) has been reasonable, but neither my doctor nor I have found a way for her to use Rx’s to build up a safety inventory in case of natural disaster.
So good for you in finding a way to deal with your particular body’s “feature” of not always giving you the expected number of days of sensor usage.
Thanks for the thoughtful feedback, @Jim10. I too read several anecdotes about the G6 vs G7 a few years back and made the same decision to stick with the G6. I wish my body was still able to extend the G6 sensor past its warranteed 10 days but I can’t.
I’ve found sensors more difficult than the transmitters to build up a reasonable emergency supply as the transmitters can last up to 110 days or 20 days beyond its warranty period. I think using 3 per year sensor replacements plus making sensor replacement claims on hard failures may be viable for me. I shall see.
Just to note some points of resistance to prescribing more than 3/month when it comes to medicare part B:
Medicare Part B pays a fixed amount to DME companies for a 30 day supply of sensors. $261.64 in 2024.
Dexcom has built up years of goodwill doing sensor replacements for anything. Abbott too. It has created a system where docs didn’t need to prescribe more and DME companies didn’t need to ship more.
If chart notes are still part of the WOPD there needs to be a history of you telling the doc about sensors failing.
The DME company, not medicare, is going to give your doc a hard time, and we all know how much fun DME companies are to deal with their easy and quick appeal processes.
Nobody reported anything for years and we ended up with very few devices operating to reported standards. That’s why they had to start these surveillance program on glucometers: DTS BGMS Surveillance Program
Manufacturing process change. Management changes. Device performance drifts over time and over different models.
I had a terrible string of sensors a while back that only lasted 8-9 days. When I complained about that to my Endocrinologist, he tried to write a prescription that said I needed to change the sensors every 9 days. Medicare would not go for it. I have learned that if I try to wear my sensor anywhere other than on the back of my upper arms, I only get 8 - 9 days. With the arms, I get the full 10 days … most of the time.
Thanks for sharing your experience, @SherryAnn. It’ll ensure I don’t waste mine or my doctor’s time trying that tactic.
I’ve mostly worn my CGM sensor on my chest recently. I’ve used the back of my arms years ago but with losing dexterity in my right arm and hand from a stroke, I’ve discarded the idea of using the back of my arms.
I may reconsider that idea as my left hand is still capable. I could place a sensor on the back of my right arm. And maybe if the Dexcom G7 works better than I expect, my impaired right hand may be dextrous enough to place a sensor on the back of my left arm. I shall see.
Sensor failures can be reported on online and seems to automatically become a replacement request. Dexcom disapproved a request to replace a sensor that failed on the last day. All others have been approved.
G6 total sensor failures have become rare for me. I’ve had fairly good success bringing sensors that are wildly out of cal after startup by going stepwise, ie. 90 out of cal as steps of 45 or 30 instead of one step of 90. And if a sensor seems to become confused, the restart hack often clears things allowing a good run.
