What Is a Full-Barrier CGM Underpatch? Solid No-Hole Underpatches Explained

Most people are familiar with an overpatch: adhesive that goes around or over the edges of a wearable after it is applied. An underpatch does the opposite. It is placed on the skin first, and the compatible CGM or pump wearable is applied over it.

The 2-inch Freedom Underpatch™ is a solid, full-barrier design with no center hole. Its purpose is to create a continuous layer between the skin and the compatible device adhesive.

What does “full barrier” mean?

Some underpatch designs have a large opening in the middle. A full-barrier design instead keeps the patch material continuous across the entire intended barrier area. The wearable is then applied according to the accessory and device instructions.

The basic layer order is:

Skin → Freedom Underpatch™ → compatible CGM or pump wearable → optional compatible overpatch or guard.

Underpatch vs overpatch

An underpatch and overpatch are not interchangeable. The underpatch sits beneath device adhesive. The overpatch is applied after the device and supports the surrounding adhesive area.

For a more complete comparison, read CGM Underpatch vs Overpatch: What's the Difference?

Why would someone choose a solid underpatch?

People shop for underpatches when they want an additional material layer between their skin and a compatible wearable adhesive. Skin reactions have many possible causes, so an underpatch should not be treated as a diagnosis or medical treatment. Anyone experiencing significant irritation should contact a healthcare professional and follow the device manufacturer's guidance.

Can you still use an overpatch or guard?

Depending on the exact product combination, customers may use compatible protection above the wearable as well. For example, an underpatch can address the beneath-the-device layer while an overpatch addresses surrounding adhesive support. A reusable guard or Freedom Band can address physical protection.

Check compatibility before applying

Underpatch sizing and application are device-specific. The Freedom Underpatch™ listing identifies compatible wearables, including Dexcom G7-family/Stelo, FreeStyle Libre 3-family, Simplera and MiniMed Instinct applications. Always check the current product listing and the wearable manufacturer's instructions before use.

Important: Freedom Underpatch™ is an accessory and is not intended to diagnose, treat or prevent a medical condition. Stop use and seek appropriate medical guidance if you experience concerning skin symptoms.