The Dexcom G7 stays on reliably when you get three things right: clean, dry skin before application, proper pressure after insertion, and reinforcement with the included overpatch or additional adhesive products. Most sensors fall off because of oil or moisture on the skin at the time of application, poor placement choices, or edges that lift and catch on clothing. Here’s how to prevent each of those problems.
Start With Properly Cleaned Skin
Wash the insertion site with an oil-free, antimicrobial soap and dry it thoroughly. This is the single most important step. Any residue from lotions, moisturizers, or natural skin oils creates a barrier between the adhesive and your skin, weakening the bond from the start. Do not apply any lotion or oil-containing moisturizer to the area.
Humidity matters too. Don’t insert your sensor right after a shower or bath, and avoid steamy bathrooms. If your skin still feels damp, use a hairdryer on a cool setting or move to a dry room before applying. For skin that tends to sweat, apply an unscented solid or spray antiperspirant in an oval shape on the site, wait 10 to 15 minutes, then insert the sensor in the clean center of that oval. This keeps moisture from undermining the adhesive over the following days.
Choose the Right Spot
The back of the upper arm is the recommended site for adults, and Dexcom’s own research confirms it delivers the best performance. For children ages 2 to 6, the upper buttocks is also approved. Beyond those options, the specifics of where you place it on the arm make a real difference in how long it stays put.
Pick a spot that is at least 3 inches from any insulin pump infusion set or injection site. Avoid areas near waistbands, scarring, tattoos, irritated skin, or bony areas. Most importantly, think about your daily life: choose a location unlikely to be bumped, pushed, or compressed while you sleep. Sensors that get snagged on doorframes, seat belts, or clothing are the ones that peel early.
Apply Pressure Immediately After Insertion
Right after you insert the sensor, rub firmly around the entire adhesive patch three times. For extra pressure, use the back of your fingernail. Smooth out any wrinkles in the patch as you go. Wrinkled edges are the starting point for peeling, so getting them flat against your skin right away extends the life of the adhesive significantly. Body heat activates the adhesive further, so this initial rubbing does more than you might expect.
Use the Included Overpatch
Every G7 box includes an overpatch, and Dexcom specifically recommends using it to keep the sensor in place for the full wear session. To apply it correctly, peel off the clear liners one at a time without touching the white adhesive area. Use the colored tab to center the overpatch around the sensor (a mirror helps if you’re placing it on the back of your arm). Rub around the overpatch, then use the tab to peel off the colored liner and rub again. This two-step rubbing ensures full contact with your skin.
Add a Liquid Adhesive for Extra Hold
If the standard adhesive and overpatch aren’t enough, liquid adhesive products applied before insertion can dramatically improve staying power. Two popular options:
- Skin Tac: A hypoallergenic, latex-free wipe that leaves a tacky residue on the skin, improving how well the sensor patch grips. Wipe it in an oval around where the adhesive will sit, but leave the center (where the sensor filament enters the skin) clean. Let it dry completely before inserting.
- Mastisol: A clear, latex-free liquid available in single-use vials. It’s not water-soluble, so it holds up well against sweat and moisture. Apply it the same way: around the adhesive area, avoiding the sensor insertion point, and let it dry fully before placing the sensor.
Both products are well tolerated with very few allergic reactions. They’re frequently used alongside overpatches or transparent dressings for a belt-and-suspenders approach.
Barrier Films That Protect and Stick
If your skin reacts to the G7 adhesive, a barrier film applied before insertion can protect your skin while still allowing the patch to adhere. Apply the barrier film in an oval shape on clean skin and let it dry completely before placing the sensor in the center of the oval.
Several options work well. Smith and Nephew’s Skin Prep is a popular choice because it offers moderate skin protection while also mildly enhancing adhesion. IV Prep wipes add a waterproof, breathable barrier with antiseptic properties. SurePrep from Medline can even be used on damaged or sensitive skin. For stronger protection, hydrocolloid dressings like DuoDERM or Hydro Seal bandages provide a thicker waterproof layer underneath the sensor adhesive. Cut an oval opening in the center so the sensor filament still contacts your skin directly.
Third-Party Overpatches for Active Lifestyles
The included overpatch works for many people, but if you swim, exercise heavily, or live in a humid climate, aftermarket patches offer stronger adhesion and longer wear. Several brands have built a following in the diabetes community.
- ExpressionMed: Nonwoven material that won’t fray, with hypoallergenic adhesive free of tree saps, resins, and rubbers. The company rates them for 10 to 21 days of wear, and they’re sweat-proof and waterproof.
- Not Just a Patch: Made from 96% cotton and 4% spandex with medical-quality hypoallergenic adhesive. A wave pattern design allows the patch to stretch and breathe, making it a strong choice for athletes and heavy sweaters.
- GrifGrips: Uses a compact mesh fabric with water-resistant adhesive designed for flexibility and breathability.
- Simpatch: Round or oval, waterproof, made from latex-free 100% acrylic adhesive. Breathable but extremely durable.
- A Silly Patch: Made from water-resistant 3M medical device tape that conforms to the body and stays breathable.
Any of these can be applied over your sensor and the Dexcom overpatch for additional security, or used as a replacement for the included overpatch if you prefer a different material.
Managing Water Exposure
The G7 is waterproof and rated for submersion up to 8 feet for 24 hours. So showering, bathing, and swimming won’t damage the sensor itself. The adhesive patch, however, is a different story. Dexcom notes directly that the patch stays on longer when kept dry.
If you swim regularly or take long showers, pat the patch dry afterward rather than rubbing it. Adding a liquid adhesive like Skin Tac before insertion and a waterproof third-party overpatch gives you the best chance of making it through the full wear period without lifting. Some people also wrap the arm loosely with a cohesive bandage (the kind that sticks to itself) during pool sessions, then remove it afterward.
Troubleshooting Edges That Lift
If the edges of your patch start peeling mid-session, you can often save it. Apply a transparent film dressing like Tegaderm HP (the “HP” stands for Holding Power, and it grips more firmly than standard Tegaderm) or an IV3000 patch over the sensor to press the lifting edges back down. Opsite Flexifit comes in rolls you can cut to size for a custom fit. These thin transparent films also work as adhesive enhancers when layered over the existing sensor tape, though they’re more prone to peeling with sweat and humidity than the thicker aftermarket patches.
Avoid the temptation to use regular household tape or bandages that aren’t designed for multi-day skin contact. They trap moisture, irritate skin, and often fail faster than doing nothing at all.