Switched to the Dexcom G7? What to Do With Your Old G6 Sensors

Almost nobody switches CGM systems on an empty cupboard. The prescription changes, the pharmacy sends the new one, and a few boxes of the old sensors are simply left over. They were paid for, they are sealed, and they are now completely useless to the person holding them.

That is worth being blunt about, because it is the whole problem. A G6 sensor does not work with a G7 setup. They are different systems, not different versions of the same one, so there is no adapter, no workaround, and no reason to keep the box "just in case". The same is true in the other direction, and it is now true again for anyone moved from the 10-day G7 sensor to the 15-day one.

What you are actually holding

Open the bag properly before deciding anything, because a CGM changeover usually leaves three different things behind and they are not the same:

• Sensors. The boxed, single-use part. This is almost always the bulk of what is left and the part with real value.
• Transmitters. G6 used a separate reusable transmitter. G7 builds it into the sensor, so a G6 transmitter has no home in the new system.
• Receivers. The handheld display. Many people never used one because they read the sensor on a phone, so these often turn up unopened.

All three are things a buyer will look at. People routinely throw away the transmitter and the receiver while carefully keeping the sensors, which is the wrong way round more often than you would expect.

The expiry rule almost everyone gets wrong

The standard advice online is that once the date has passed, diabetic supplies are worthless. For test strips that is correct and you should follow it — a degraded strip gives an inaccurate reading, and an inaccurate glucose reading is a safety problem rather than a bargain.

It is wrong about CGM sensors, and specifically it is wrong in one direction only. Expired Dexcom G7 sensors still have value, at a reduced rate rather than nothing at all. Expired Dexcom G6 sensors do not.

That single distinction is why this page exists. Boxes get binned every week on the strength of advice written about something else. Check which generation you are holding and what the date says before anything goes in the trash.

What makes a box sellable

Four things, and they are easy to check in a couple of minutes:

1. Factory sealed. Unopened, in the original packaging. Once a box has been opened nobody downstream can verify what happened to it while it was open, so an opened box cannot be resold at any price.
2. In date, with the G7 exception above.
3. Not funded through a government program. Supplies obtained that way cannot be resold. This is about the funding route, not about you, and nobody is asked to prove how a box came into their possession.
4. Described accurately. Generation, box count, and the dates as printed. A figure quoted against a rough description is a figure that changes when someone sees the boxes.

Photograph the sealed boxes with the expiry date and lot number visible before they go anywhere, and keep those photographs until you have been paid. Do not open one to photograph the contents — opening it destroys the only thing that made it sellable.

Where it goes from here

For a handful of boxes, the state pages show who is nearest to you and whether an in-person handover is realistic where you live. Mail-in works from anywhere and the label costs you nothing.

If the switch left you with a lot — a pharmacy changing its stocked line, a supply company clearing a discontinued product, or a reseller holding a hundred pieces or more — that is a different conversation, and the bulk page is the right starting point. Mixed generations and mixed dates are normal in a lot that size and do not need sorting before you get a number.