CGM Sensor Lifespan and Replacement

Typical Wear Times

CGM sensors are single-use devices with a set wear period. The exact duration depends on the product and the country label.

• Dexcom G7 is indicated for up to 10 days, with a 12-hour grace period.
• [FreeStyle Libre](/glossary/#term-freestyle-libre) 3 is commonly labeled for 14 days, while Libre 3 Plus is listed in current Abbott materials for up to 15 days.
• Guardian 4 is generally used for about 7 days and is approved for the back of the upper arm.
• Stelo by Dexcom is an over-the-counter biosensor with sessions lasting up to 15 days.

Do not restart a disposable sensor unless the manufacturer instructions for that exact product allow it.

Why Sensors Fail Early

Early failure is usually mechanical, adhesive-related, or signal-related. A sensor may loosen after sweating, swimming, friction from clothing, or skin prep that leaves lotion or oil behind. Insertion problems can also matter: bleeding, filament movement, scar tissue, or a site that bends often can reduce performance.

Signal checks may trigger errors when the system cannot confirm reliable readings. Medtronic, for example, describes Sensor Updating as a safety check that often clears, but may require replacement if it persists.

Warranty and Support

If a sensor fails before the expected wear period, document the date, lot or serial number, error message, insertion site, and what troubleshooting you tried. Dexcom states that confirmed product failures during the intended lifetime are replaced without limit, while non-product issues may qualify for courtesy replacement. Other manufacturers also have support channels for failed sensors.

Maximizing Wear Time

• Apply sensors to approved sites only.
• Start with clean, dry skin and let alcohol dry fully.
• Avoid lotions, sunscreen, and oils before insertion.
• Use the included overpatch or tape when instructed.
• Place sensors away from waistbands, bra straps, seat belts, and high-friction areas.
• Rotate sites to reduce irritation and scarred tissue.

What To Do After Failure

If readings are missing or do not match symptoms, use a [blood glucose](/glossary/#term-blood-glucose) meter for treatment decisions. Replace the sensor when the app or receiver says the sensor failed, when the filament pulls out, or when adhesive loss exposes the sensor. Then contact support promptly, while the device details are still easy to find.