Applying a Dexcom continuous glucose monitor takes about two minutes once you know the steps. The process is slightly different depending on whether you have a G7 or G6, but both use a spring-loaded applicator that inserts a tiny sensor wire under your skin with the push of a button. Here’s exactly how to do it, from skin prep through your first reading.
Choose Your Sensor Site
For adults and children age 7 and older, the back of the upper arm is the primary spot for both the G6 and G7. Children ages 2 to 6 can also wear the G7 on the upper buttocks. The G6 additionally allows abdomen placement for adults.
Pick a spot that’s relatively flat with a layer of fat underneath. Avoid areas where skin folds, where clothing rubs (like a waistband), or where you tend to sleep on at night. Stay at least 3 inches away from any insulin pump infusion site or injection spot. Skip skin with scarring, tattoos, or heavy hair. If you need to remove hair, use electric clippers rather than a razor to avoid irritating the skin.
Prepare Your Skin
Good skin prep is the single biggest factor in whether your sensor stays put for the full wear period. Wash your hands first, then clean the site with an alcohol wipe and let it air dry for at least 10 seconds. Don’t apply any lotion, oil, or moisturizer to the area beforehand.
If your skin tends to sweat, apply unscented solid or spray antiperspirant around the site in an oval shape, leaving the center bare where the sensor will actually sit. Wait 10 to 15 minutes for it to dry before inserting. If you’ve had adhesive irritation in the past, a barrier film wipe (like Cavilon No Sting or Skin Prep) applied in that same oval pattern can create a protective layer between the adhesive and your skin. Let any barrier product dry completely before moving on.
Insert the Sensor (G7)
Grab the G7 applicator and unscrew the cap. Save the cap because the 4-digit pairing code you’ll need for your phone or receiver is printed on it. Don’t touch the inside of the applicator where the adhesive and sensor wire are housed.
Press the applicator firmly against your skin and hold it there. Push the orange button on top. You’ll hear a click and feel a quick pinch as the spring-loaded needle places the sensor wire just under the skin, then retracts. Most people describe it as less painful than a finger stick.
Once the sensor is in, rub firmly around the adhesive patch three times in a circular motion, then press gently on the sensor body for about 10 seconds. This activates the adhesive bond and helps it conform to your skin.
Apply the G7 Overpatch
Each G7 sensor comes with an overpatch in the box. Peel off the clear liners one at a time without touching the white adhesive side. Use the colored tab to center the overpatch around the sensor, then rub around it to smooth it down. Peel off the remaining colored liner and rub around the patch one more time. The overpatch adds a significant layer of security, especially during exercise or sweating. For the first 12 hours, try to keep the area as dry and sweat-free as possible. The longer you can keep it dry early on, the better it will stick for the rest of the wear period.
Insert the Sensor (G6)
The G6 has a two-part process. First, peel open the sensor applicator package, remove the safety guard, and place the applicator against your skin. Press the plunger to insert the sensor, then pull the applicator away. The adhesive patch stays on your skin with the sensor wire underneath.
Next, snap the separate transmitter into the sensor housing. You’ll hear two clicks as it locks into place. The transmitter is the small, reusable component that sends data to your phone or receiver. Unlike the G7, which has the transmitter built into each disposable sensor, the G6 transmitter gets reused across multiple sensor sessions.
Pair With Your Device
Open the Dexcom app on your phone (or turn on your Dexcom receiver). For the G7, enter the 4-digit pairing code from the applicator cap. The app will confirm it’s connected and begin the warmup period. The G7 takes 30 minutes to warm up before you see your first glucose reading. The G6 takes 2 hours.
During warmup, the sensor is calibrating to your body’s interstitial fluid. You won’t see any data on your screen until warmup is complete, so don’t worry if the app shows a countdown timer instead of a number.
What to Do if Something Goes Wrong
A small amount of bleeding at the insertion site is normal and happens when the sensor wire nicks a tiny blood vessel. This doesn’t necessarily mean you need to remove the sensor. If bleeding is minor and stops on its own, you can leave it in place and monitor your readings for accuracy. If bleeding continues or you see blood pooling under the adhesive, contact Dexcom’s technical support line (available 24/7) and they’ll walk you through whether to replace it. Dexcom typically sends free replacements for sensors that fail or cause problems during insertion.
If the adhesive starts peeling at the edges during the wear period, you can reinforce it with medical tape or additional adhesive patches like Tegaderm or IV3000 placed over the top. Some people also apply a thin layer of liquid adhesive (like Skin Tac) around the patch edges to reseal them.
Removing the Sensor
When your sensor session ends (10 days for the G6 or standard G7, 15 days for the G7 15 Day), peel the sensor off slowly. The best technique is to fold the adhesive back on itself at a low angle rather than pulling straight up. Use your free hand to press the skin down and away from the patch as you peel.
If the adhesive resists, an adhesive remover wipe makes a big difference. Products like Uni-Solve, Tac Away, or even household oils (baby oil, coconut oil, olive oil) will dissolve the adhesive bond. Rub the remover under the edge of the patch and work your way inward. This is especially helpful if you used barrier films or extra adhesive products during application.
Tips for Your First Time
If you’re applying a Dexcom for the first time, ask someone to help, especially if you’re placing it on the back of your arm where you can’t easily see. A mirror also works well for positioning. Practice pressing the applicator against your skin firmly before pushing the button. Hesitating or holding it too loosely is the most common cause of poor insertions. One confident push is all it takes.
Rotate your sensor site each time you apply a new one. Using the same spot repeatedly can cause skin irritation or scarring that affects sensor accuracy. Alternate between your left and right arm, or between different areas of the same arm, giving each spot at least a week to recover between uses.