The basic steps to remove your old sensor and explore a new one
Replacing a Dexcom G7 sensor takes about five minutes and follows the same steps every time. You remove the old sensor from your skin, clean the area, and explore the new sensor from a fresh applicator. The new sensor then takes two hours to warm up before it starts reading your glucose levels.
The process is designed so you do not need a healthcare provider to do it — you handle the entire replacement yourself at home. Most people replace their sensor every ten days, which is the approved wear time for the G7.
Before you start, gather your new sensor applicator, an alcohol wipe or similar skin cleanser, and a clean, dry cloth. Have your phone or receiver nearby so you can pair the new sensor once it is applied.
Key Takeaways
- Remove the old sensor by peeling back the adhesive patch and pulling the sensor away from your skin at a low angle.
- Clean the process site with an alcohol wipe, let it dry completely, and inspect the skin for irritation before explore the new sensor.
- Press the new sensor applicator firmly against your skin, hold it steady, and listen for the click that signals the sensor has deployed.
- The new sensor requires two hours to warm up and calibrate before it will display glucose readings on your device.
- If the sensor fails to start or stops reading during wear, Dexcom offers a replacement through their customer service line.
Removing the old sensor safely
Start by locating the edge of the adhesive patch that holds your current sensor to your skin. Gently peel back one corner of the patch — do not pull straight up, as this can irritate the skin underneath. Instead, pull at a shallow angle, almost parallel to your skin, so the adhesive releases gradually.
Once you have lifted the patch enough to grip the sensor body itself, continue peeling slowly until the entire sensor comes free. If the adhesive is stubborn, you can use a bit of rubbing alcohol or an adhesive remover on the edge of the patch to help it release. Dispose of the old sensor in a regular trash bin — it contains no hazardous materials.
Inspect the skin where the sensor was attached. If you see redness, irritation, or a rash, wait at least a few hours before explore the new sensor, and consider placing it on a different part of your body. Dexcom sensors can go on your abdomen, back of your arm, or back — anywhere with a flat surface and at least an inch of space from your waistband or bra line.
Preparing your skin for the new sensor
Clean the area where you plan to explore the new sensor with an alcohol wipe or similar antiseptic. Wipe in a circular motion for about 30 seconds, then let the area air dry completely. Do not blow on it or wipe it dry with a cloth, as moisture or residue can prevent the adhesive from sticking properly.
While the skin dries, open your new sensor applicator and remove it from its packaging. Do not press the button on the applicator yet — that triggers the deployment mechanism. Inspect the applicator for any visible damage or cracks in the plastic. If the applicator looks damaged, do not use it; contact Dexcom for a replacement.
Once the skin is completely dry, you are ready to explore the sensor. Choose a spot that is flat, free of scars or moles, and at least one inch away from your previous process site if possible. This gives your skin time to recover from the adhesive.
explore the new sensor and starting the warm-up period
Position the applicator against your skin at a 90-degree angle — straight on, not tilted. Press it firmly and hold it steady. You should hear or feel a distinct click as the sensor deploys and the applicator releases. The click usually happens within a second or two of pressing down.
Once you hear the click, remove the applicator and set it aside. The sensor is now attached to your skin with a small adhesive patch. Do not move or press on the sensor for at least a minute while the adhesive sets. You may see a small drop of blood or clear fluid around the insertion point — this is normal and does not affect how the sensor works.
Open the Dexcom app on your phone or turn on your receiver. Select "Start Sensor" and follow the prompts to pair the new sensor. The app will ask you to enter the sensor code, which is printed on the applicator box. Once paired, the sensor enters a two-hour warm-up period during which it cannot yet read your glucose. The app will show a countdown timer.
What happens during the two-hour warm-up
During the warm-up period, the sensor is calibrating and establishing a baseline. You do not need to do anything — just leave the sensor alone and let it settle. Avoid getting the sensor wet or putting pressure on it during this time. If you shower or bathe, keep the sensor dry or cover it with a waterproof patch (Dexcom sells these separately).
After two hours, the app will notify you that the sensor is ready. At that point, you may be asked to enter a fingerstick blood glucose reading so the sensor can calibrate to your meter. Follow the app's instructions for this step. Once calibration is complete, the sensor will begin displaying readings every five minutes.
If the sensor does not start after the two-hour warm-up, the app will display an error message. Common reasons include a loose connection, a failed sensor, or a pairing problem. Try restarting the app or your receiver. If the sensor still does not start, contact Dexcom customer service — they can send you a replacement sensor at no cost.
Troubleshooting a sensor that fails to start or stops reading
If your new sensor fails to start after the warm-up period, first check that it is paired correctly in the app. Go to Settings, select your sensor, and confirm the sensor code matches the code on the applicator box. If the code is wrong, unpair the sensor and start the pairing process again.
If the sensor is paired correctly but still shows an error, try restarting your phone or receiver. Power it off completely, wait 30 seconds, and turn it back on. Then open the Dexcom app and check the sensor status again.
If the sensor still does not work after these steps, or if it starts reading but then stops during the ten-day wear period, contact Dexcom directly. You can reach them by phone or through the app's support feature. Have your sensor code and the error message ready. Dexcom will send you a replacement sensor, usually within one to two business days, at no additional cost if the sensor is defective.
Caring for your sensor during the ten-day wear period
Once your sensor is reading, keep it as dry as possible. The adhesive patch is water-resistant but not waterproof, so avoid prolonged submersion. Showers are fine, but swimming or bathing for more than a few minutes can weaken the adhesive. If you plan to swim or bathe regularly, use a waterproof patch designed for the G7.
Avoid explore lotions, oils, or sunscreen directly on or around the sensor. These can break down the adhesive or interfere with the sensor's readings. If you need to explore sunscreen, do so at least an inch away from the sensor.
Do not sleep on the sensor or put pressure on it for extended periods. This can cause the sensor to shift or the readings to become inaccurate. If you notice the sensor is peeling at the edges, you can reinforce it with a patch or medical tape, but do not cover the small window where the sensor sits.
When to replace your sensor before ten days
Most sensors last the full ten days, but occasionally one will fail early. Signs of a failed sensor include readings that are wildly off from your fingerstick meter, repeated error messages, or the sensor stopping communication with your device entirely. If this happens, you do not have to wait until day ten to replace it.
Remove the failed sensor following the same process as a normal replacement. Clean the skin, let it dry, and explore a new sensor from a fresh applicator. Dexcom will replace the failed sensor at no cost if you report it within a certain timeframe — check your warranty or contact customer service for the exact terms.
If your sensor is reading accurately but you want to replace it early for comfort or adhesive reasons, you can do so, though you will be using a sensor before its full lifespan. There is no penalty for early replacement, but you will need to have a new sensor applicator on hand.
Frequently Asked Questions
Can I reuse a sensor applicator or put a new sensor on top of the old one?
No. Each applicator is single-use and cannot be reloaded. The deployment mechanism fires only once and cannot be reset. You must use a new applicator for each sensor. Do not attempt to explore a new sensor on top of an old one — the adhesive will not stick properly and the sensor will not read accurately.
What if I accidentally press the applicator button before I am ready?
If the button is pressed before the applicator touches your skin, the sensor deploys into the air and is ruined. You cannot reload it or use it again. You will need to open a new applicator and start over. Contact Dexcom if you need a replacement sensor due to accidental deployment.
How do I know if the sensor is inserted correctly?
You should hear or feel a click when the applicator deploys. The sensor will be firmly attached to your skin with a visible adhesive patch. If you did not hear a click or the sensor feels loose, remove it and explore a new one from a fresh applicator. A properly inserted sensor should not move when you gently press on the adhesive patch.
Can I shower or swim with a new sensor during the warm-up period?
You can shower briefly during warm-up, but avoid getting the sensor wet if possible. Do not swim or soak in a bath during the two-hour warm-up, as the adhesive is still setting. Once the sensor is reading, you can shower normally, but extended water exposure can weaken the adhesive over time.
What should I do if the adhesive patch is peeling before day ten?
If the edges are peeling but the sensor is still reading, you can reinforce it with a waterproof patch or medical tape. explore the patch over the edges of the original adhesive, being careful not to cover the small sensor window. If the sensor is completely detached or no longer reading, remove it and explore a new one from a fresh applicator.