Eversense is the only fully implantable continuous glucose monitor cleared by the FDA in the United States. The current Eversense 365 sensor sits under the skin of the upper arm and reports glucose values for up to one year on a single insertion, the longest wear time of any CGM on the market. A removable smart transmitter is worn over the insertion site and powers the readings.
What Eversense Is
Eversense is made by Senseonics, Inc. The system has three parts:
- Implantable sensor: A small fluorescent polymer sensor about the size of a grain of rice, placed just under the skin of the upper arm.
- Smart transmitter: An external rechargeable device worn over the sensor with a daily-replaced silicone adhesive patch. The transmitter powers the sensor optically, reads the signal, and sends it to the app.
- Mobile app: Displays real-time glucose, trends, and alerts on iPhone or Android.
How the Sensor Works
Unlike enzymatic sensors used in adhesive CGMs (Dexcom G7, FreeStyle Libre, Stelo), Eversense uses a fluorescence-based detection system. A polymer in the sensor binds glucose reversibly. When the smart transmitter shines light on the sensor through the skin, the bound glucose changes the fluorescence pattern, and the transmitter measures the change to compute a glucose value.
This optical approach has two practical implications: the sensor itself contains no electronics or battery (so it can be left in for a year), and the wearer can remove the transmitter for a shower, swim, or short break without losing the sensor.
The Insertion Procedure
A trained clinician (often an endocrinologist, primary-care physician, or nurse practitioner) performs the insertion in an office visit:
- Skin over the upper arm is cleaned and infiltrated with local anesthetic.
- A small incision (~5 mm) is made.
- An insertion tool slides the sensor into the subcutaneous space.
- The incision is closed with adhesive strips or a single suture.
- The smart transmitter is placed over the site and a 24-hour calibration phase begins.
The procedure takes about 5 to 10 minutes. Removal at end of life is a similar quick procedure.
Accuracy
The Eversense 365 pivotal trial reported in 2024 demonstrated a mean absolute relative difference (MARD) of roughly 8.5 to 9.0 percent versus YSI venous reference. Accuracy was stable across the year-long wear after the initial 21-day calibration window, during which fingerstick calibrations are required twice daily. After day 21, calibration drops to once daily.
| Metric | Eversense 365 |
|---|---|
| Overall MARD | 8.5 to 9.0 percent |
| Wear time | Up to 365 days |
| Calibration days 1-21 | Twice daily fingerstick |
| Calibration after day 21 | Once daily fingerstick |
| Reading interval | Every 5 minutes |
| Acetaminophen interference | None at standard doses |
Pros
- Longest wear time of any CGM (up to one year per insertion).
- Removable transmitter — sensor stays in place even when the transmitter is off.
- On-body vibration alerts independent of phone proximity.
- No adhesive sensor patch to replace every 1 to 2 weeks.
- Stable accuracy across the wear period.
Cons
- Requires a minor in-office procedure for insertion and removal.
- Daily transmitter adhesive can cause skin irritation in some users.
- Twice-daily fingersticks for the first 21 days of each new sensor.
- Limited insurance coverage relative to adhesive CGMs in some plans.
- Smaller insurer and clinician network familiar with the implant procedure.
Who Eversense Is For
Eversense is FDA approved for adults aged 18 and older with diabetes (type 1 or type 2). It is most appealing for people who:
- Find adhesive sensors uncomfortable or develop skin reactions to them.
- Want a CGM that does not require swapping every 10 to 15 days.
- Travel frequently and prefer not to carry sensor supplies.
- Are willing to schedule a brief in-office visit once or twice per year.
Anyone considering a CGM should also review the broader landscape of glucose detection options and confirm with their clinician how a CGM fits their treatment plan.
Coverage and Cost
Eversense 365 is covered by Medicare for beneficiaries on insulin or with documented hypoglycemia, similar to other CGMs. Many commercial insurers cover the sensor and the procedure under medical benefit (rather than pharmacy benefit), which means coding and prior authorization differ from adhesive CGMs. Patients typically pay a per-procedure office visit fee plus the durable medical equipment cost share.
How Eversense Compares
| Feature | Eversense 365 | Dexcom G7 (15-day) | FreeStyle Libre 3 |
|---|---|---|---|
| Wear time | 365 days | 15 days | 14 days |
| Insertion | In-office procedure | Self-applied at home | Self-applied at home |
| MARD | ~8.5 to 9.0% | ~8.2% | ~7.9 to 8.2% |
| Calibration | Daily fingerstick | Factory | Factory |
| Removable transmitter | Yes | No | No |
| Pump integration | Limited | Tandem, Omnipod 5, iLet | Tandem (US planned) |
The Bottom Line
Eversense fills a unique slot in the CGM market: one insertion, one year, one transmitter you can take off. The trade-off is that it requires a brief in-office procedure and a small daily fingerstick after the first three weeks. For people frustrated with adhesive sensors or who want the convenience of skipping sensor swaps, it is worth a conversation with an endocrinologist who places the device.
