How to Keep a CGM Sensor On for the Full Wear Time

The short answer

Sensors usually come off for one of three reasons: the skin was not clean and dry at insertion, the sensor is somewhere that gets caught on clothing or doorframes, or sweat has broken the adhesive down. Prep and placement fix most of it before you ever need extra tape.

Prep the site properly

1. Wash the area with plain soap and water. Skip anything with moisturizer, oil, or fragrance — lotion is the enemy of adhesive.
2. Dry completely. Not mostly dry. Completely.
3. If you use alcohol, let it evaporate fully before applying. Applying to damp skin is a guaranteed early failure.
4. Press the adhesive down firmly around the whole edge for 30 seconds after insertion. Body heat helps it bond.

Give it an hour before showering or exercising if you can. That first hour is when the bond sets.

Placement matters more than people think

The back of the upper arm is the approved site for both Dexcom G7 and FreeStyle Libre 3 in adults. Within that area, aim for the fleshy part, slightly toward the back — not so far forward that a shirt sleeve drags on it, and not right where a seatbelt, backpack strap, or car door catches.

Alternate arms with each new sensor. It gives skin time to recover and reduces irritation over months of wear.

Sweat, heat, and water

Both sensors are water resistant for showering and swimming within the manufacturer limits, but repeated heavy sweating is what actually loosens edges. If you work outside or train hard:

• Pat the sensor dry rather than rubbing after showers and workouts.
• Skip lotion and sunscreen directly over the adhesive.
• Rinse chlorine or salt water off the area soon after swimming.

When you need extra adhesive

Overpatches and skin prep wipes are not shipped with sensors as a standard item — we send them when you ask. If you are losing sensors early, tell us and we will add them to your order.

A few notes on using them well: apply an overpatch only after the sensor has been on and set, keep the transmitter window uncovered where the instructions require, and remove the patch slowly with the grain of your skin, not straight up.

If your skin reacts

Redness, itching, or a rash under the adhesive is worth mentioning to your clinician rather than powering through. Barrier options exist, and site rotation helps, but a persistent reaction needs a real answer — not a thicker layer of tape over irritated skin.

If a sensor fails early anyway

It happens, and manufacturers replace failed sensors. Keep the sensor and the packaging with the lot number, note the date and what happened, and contact the manufacturer support line. Let us know as well so your resupply timing stays accurate.

Your next step today

Next time you insert, do the full 30-second press and give it an hour before water. If you are still losing sensors, contact us and we will add overpatches to your next shipment.