Research study indicates that sensor accuracy is good up until 2 weeks.
“Extending CGM sensor life offers a con- venience to patients and may result in cost savings. In our study, the majority of sen- sors lasted the full 14 days, and accuracy was similar between weeks 1 and 2.”
I never do…I get at least 14 days out of mine. I am not a fan of wasting resources so I like to use them until they are almost falling off…I also use my syringes multiple times. The Dexcom has changed my life and I have had the best A1Cs of my life (been Type 1 for over 38 years). No dangerously low blood sugars…gone are the days when I wake my husband up due to convulsions after very low blood sugars while sleeping.
Thanks for posting this study link about CGM sensor longevity and accuracy. My experience mostly falls in line with what the study participants experienced. I usually get 14 days out of the sensor with week two accuracy similar to week one.
Most of the study sensor failures were related to adhesive failure. I use a technique to get the sensor to stick well for at least 14 days. I wash the site using a washrag with soap and hot water and rinse well. I then dry the site thoroughly and slightly rough up the skin with a dry towel. Once the sensor is inserted, I paint some Skin-Tac over the top of the sensor bandage. It’s important that while the bandage is still wet with Skin-Tac to not produce any movement between the bandage and the skin. Using a hair dryer on low or no heat helps speed up this process.
This process means that almost all my sensor failures are related to sensor accuracy and data dropout. Your experience may vary but this process serves me well. To remove any adhesive that sticks to the skin, I rub on baby oil. It works well without roughing up the skin much.
I use basically the same procedure as Terry4 for attaching sensors. Mine also stay on for the full two weeks with no additional taping. It is sketchy data that is usually my reason for changing.
Thank you Terry, I read something related to skin tac over the top of the bandage some months ago and has worked fine. Nowadays Im back to Enlite sensors (hopefully temporarily). 
Since I bought Opsite Flexifix this is the first time that my sensor went 14 days. Today is the 14th day.I inserted it on the 20th of March. I restarted it on the 27th and It is still working.I wonder if this is going to be typical of ever sensor? Right now I am happy that it has gone on this long.
That’s the tape I use to keep my sensors in place. Usually, I have to ‘repair’ the tape along the way, but I generally get three weeks from a sensor before changing it – My current sensor is on Day 19, and working great.
Whether or not this becomes typical for you is fairly individual, though it does seem that 14-21 days is pretty reasonable expectation for most people. Certainly not all - some see irritation (usually adhesive), some see the sensor just stop working, and some have other issues. And not all sensors or all sites work that well for any person - I have had sensors that stopped working in just 6 days, or even less. You’ll only know how well it works for you by trying. Good luck!
As it turns out I restarted my sensor for the second time and it is giving me question marks. I will wait and see if it comes back. If not it’s probably time for a change.
How does that work?
Turns out to not be “free” but significantly discounted. The list price for 2 G5’s is over $900 and with my subscription discount, it was $199. As long as I buy 9 boxes of sensors a year, that’s the price for the transmitters.
Okay thank you!
Sent: Wednesday, April 05, 2017 at 8:51 PM
From: Daytona <tudiabetes@discoursemail.com>
Subject: [TuDiabetes Forum] [Diabetes Technology/Glucose Monitoring] Does anyone change Dexcom sensor at 7 days? 
daytona
April 6
Lisa61:
How does that work?
Turns out to not be "free" but significantly discounted. The list price for 2 G5's is over $900 and with my subscription discount, it was $199. As long as I buy 9 boxes of sensors a year, that's the price for the transmitters.
Visit Topic or reply to this email to respond.
Lisa61
April 5How does that work?
Visit Topic or reply to this email to respond.
You might want to remove your email address and the ‘Unsubscribe’-link from your post.
Do you get 14-20 days on the sensor without doing a “stop sensor - then start sensor” at the 7 day mark? i.e. just carry on as long as everything is good?
With Dex you have to do the stop-start-wait2hours routine at least every 7 days, whether you are re-starting an existing sensor or initiating a new one.
No, the sensors stop every 7 days. I just stop and restart the sensor while keeping the sensor in place. I usually get between 17-20 days per sensor.
I usually go 14 days after which the adhesive starts becoming too much of a pain to keep patching up and I swap in a new one. But with my current one I decided to go back to my belly (I’ve been a back-of-the-upper-arm guy for a while) and am several day past my third roll-over. I think this is the first time I’ve gone 21 days and more, but it’s tracking more accurately than ever and the adhesive is holding up fine. Maybe there’s a reason they want you to use that location…
Medicare covers my G5 sensors and transmitters and manages the monthly shipments through Dexcom. The sensor deliveries are based on Dexcom’s 7 day specification; the transmitters on their 90 day specification. This makes it very convenient to change sensors same day every week. I suspect this will change when Medicare updates to the G6 that has a 10 day sensor spec.
Prior to Medicare’s approval I self-payed and stretched the sensors as long as possible (but no more than 2 weeks) using whatever method worked to keep them on me.