You can change your Dexcom G6 sensor at any point before the 10-day session ends by manually stopping the session through the app or receiver. The process takes just a few taps, but planning ahead for the two-hour warmup period on the new sensor will save you from a gap in your glucose readings.
How to Stop a Session Early
Open the Dexcom G6 app on your phone, go to the main menu, scroll to the bottom, select “Stop Sensor,” and confirm by selecting “Yes.” That immediately ends the current session. If you use the Dexcom receiver instead of the app, the steps are similar through the device’s menu.
Once the session is stopped, you’re free to remove the old sensor and insert a new one whenever you’re ready. There’s no mandatory waiting period between stopping one session and starting the next.
Removing the Old Sensor
Peel the adhesive patch away from your skin slowly. To make this less painful and reduce skin irritation, slide an adhesive remover wipe underneath the tape edge as you lift it. This loosens the bond between adhesive and skin rather than pulling it off dry. Several medical-grade products work well for this, including Uni-Solve wipes, Tac Away wipes, and Detachol remover. If you don’t have a specialized product on hand, baby oil, coconut oil, or olive oil will do the job.
After removing the sensor, gently clean the area. If you’ve been wearing sensors on the same spot repeatedly, give that site a break before using it again.
Choosing a New Insertion Site
For adults, the abdomen is the approved insertion site. Children ages 2 through 17 can also use the upper buttocks. Wherever you place it, pick a spot at least a few inches away from the previous site. Rotating locations helps the skin recover and generally gives you better readings, since fresh tissue hasn’t been compressed by adhesive for the past week.
Avoid areas where clothing or a seatbelt rubs against the sensor, and steer clear of spots with scar tissue, stretch marks, or bony areas. A flat, relatively soft patch of skin gives the sensor the best contact.
Starting the New Session
Insert the new sensor using the applicator, then open the app and follow the prompts to start a new session. You’ll need to enter the sensor code printed on the back of the adhesive patch. After that, the system enters a two-hour warmup period. During those two hours, you won’t receive any glucose readings, so plan your swap accordingly. If you change the sensor right before a meal or an activity where you rely on CGM data, you’ll be flying blind for that window.
A practical approach: start the new sensor session while the old one is still running, if timing matters to you. Some users insert the new sensor (without starting it in the app) an hour or so before they plan to switch, allowing the sensor filament to settle into the tissue. Then they stop the old session, remove it, and immediately start the new sensor’s session in the app. This can shorten the effective gap in usable readings, though the two-hour warmup still applies from the moment you hit “Start Sensor.”
What to Expect in the First 24 Hours
The G6 does not require fingerstick calibrations, even after a fresh sensor insertion. That said, readings during the first day of a new sensor tend to be less precise than later in the session. The difference between your meter and the G6 may be wider than usual in those initial hours, and it generally tightens up over the first 24 hours.
If you notice the G6 reading is consistently higher or consistently lower than your meter values over several hours, and the gap falls outside what you’d expect, you can manually calibrate through the app. This is optional, not required. Only calibrate if the pattern is steady in one direction. A single off reading isn’t a reason to calibrate, since that can actually make things less accurate if the sensor is still settling in.
Transmitter Considerations
When you change a sensor early, the transmitter stays in place or gets snapped into the new sensor. The transmitter battery lasts about three months, regardless of how many sensor sessions you run during that time. Starting at three weeks before the battery runs out, you’ll begin seeing countdown warnings. When the transmitter has only 10 days of battery life left (enough for one more sensor session), you’ll get a final alert.
Changing sensors early doesn’t damage the transmitter or shorten its life. The battery drains on a clock, not per session. So if you swap sensors more frequently than every 10 days, you’ll use more sensors but the transmitter timeline stays the same.
Getting a Replacement Sensor
If you’re changing the sensor early because it failed, fell off, or gave unreliable readings, Dexcom will replace it at no cost. Contact Dexcom Tech Support as soon as possible after the failure. They’ll review what happened, and if the sensor didn’t meet its published performance expectations, they’ll send a replacement with no limit on how many times you can request one.
Even if the issue wasn’t a product defect (you accidentally knocked it off, removed it for a medical procedure, or made an application error) you may still be eligible for a courtesy replacement. It’s worth calling either way.