What You Need to Know About Implantable CGMs

Patient Expert
Eversense sensor.

Continuous glucose monitors (CGMs) are changing the way people with insulin-dependent diabetes manage their blood sugar and improve their health. When you have diabetes, research has shown that using a CGM can help improve your hemoglobin AIC levels and potentially reduces your number of dangerous episodes of hypoglycemia (low blood sugar).

In recent years, the U.S. Food and Drug Administration has approved several CGM devices – including the Dexcom, Freestyle Libre, and Medtronic Guardian Connect. You insert a sensor just below the skin, which is attached to a small transmitter that you wear. Blood sugar readings are then sent via Bluetooth to a receiver or smartphone. CGMs replace the need for you to do multiple finger stick glucose tests each day to monitor your blood sugar.

The Dexcom and Medtronic CGMs automatically transmits blood sugar readings to a transmitter or phone and allow you to receive alerts to notify you of high, low, or changing blood sugar levels. The Freestyle Libre requires that you pass a receiver or phone over the device to get your blood sugar reading.

Adding to the options available to people with diabetes, in June of 2018, the FDA approved an implantable, 90-day CGM system called Eversense, made by Senseonics.

There is another model, the Eversense XL, with a sensor that lasts up to 180 days, already available in Europe. The Eversense XL 180-day model is being studied in the U.S. and is likely to get FDA approval in 2018 or 2019.

Eversense differs from other CGM technologies in that the sensor is the size of a grain of rice. Your doctor inserts it below the skin on your upper arm. The procedure to implant an Eversense sensor involves your doctor numbing your skin, making a tiny incision, and using a tool to insert the sensor. A similar procedure is followed for removal.

As with other CGMs, you need to wear an external transmitter to transmit blood sugar readings to a receiver, smartphone, or smartwatch. Like the Dexcom and Medtronic CGMs, Eversense gives you alerts to high, low, or changing blood sugar levels and the accompanying software allows you to track your results over time.

Eversense display.
Eversense display.

Is Eversense right for you? Let’s look at the pros and cons.

Eversense CGM positives

Dexcom, Medtronic, and Freestyle Libre CGM sensors last from seven to fourteen days. The Eversense sensor lasts up to 90 days.

You only need to have the Eversense inserted four times per year, compared to up to 52 insertions per year for other CGM technology.

Research shows that Eversense is more accurate than the Dexcom and Freestyle Libre. A study, published in the American Diabetes Association journal Diabetes found that all three devices gave blood sugar readings that differed somewhat from traditional glucose meters. The Eversense was most accurate, however, with a relative difference of 14.8 percent, compared to 16.3 percent for the Dexcom G5, and 18 percent for the Freestyle Libre.

The Eversense sensor is inserted under the skin on your arm. Since many people with diabetes develop scar tissue in areas of the body such as the abdomen where they wear insulin pumps, inject insulin, or wear a CGM sensor, use of Eversense bypasses these areas.

Eversense negatives

Because the Eversense requires a transmitter worn over the sensor, like all CGMs, you still wear something externally.

A physician must insert the sensor during an in-office procedure. Having the Eversense inserted requires scheduling a doctor’s visit, potential waiting time at the doctor’s office, having the insertion procedure, and travel time to and from the doctor. Other CGM technologies can be inserted in minutes by users at home

Your skin needs to be numbed before your doctor inserts an Eversense sensor. Your skin requires no numbing before you insert sensors for other CGM devices.

After sensor insertion, Eversense’s manufacturer Senseonics recommends that you avoid soaking in a tub, swimming, or doing strenuous activities for five days. Other CGM systems have no such cautions after sensor insertion.

The warmup and calibration period for Eversense is approximately two days, during which you need to use fingerstick glucose testing. Warmup and calibration of a Freestyle Libre takes 12 hours. The warmup and calibration period for both Dexcom and Medtronic Guardian Connect is two hours.

The Eversense transmitter has limited water-resistance for up to 30 minutes when submerged. Freestyle Libre CGMs are water-resistant and can be worn while bathing, showering, or swimming but should not be submerged deeper than 3 feet or for more than 30 minutes. Medtronic Guardian Connect CGMs can be submerged for up to 7.5 feet for 10-minute periods. Dexcom CGM transmitters are water-resistant and can be submerged under 8 feet of water for up to 24 hours without damage or failure.

Should you consider using the Eversense CGM?

Using any CGM technology has many proven benefits for people with diabetes. If you are interested in CGM, your choice of CGM technology is likely to be dictated primarily by the cost of the device you are choosing, and whether your health maintenance organization (HMO), health insurer, or Medicare will cover those costs.

At present, CGM technology is covered for some patients by some health insurers, HMOs, and Medicare. According to Eversense’s manufacturer, they anticipate that the annual costs will be similar to costs for Dexcom and Medtronic CGM devices. (Freestyle Libre is significantly less expensive than other CGM technology.)

The bottom line: If you are interested in Eversense, consult with your doctor and discuss the pros and cons. You should also contact your insurer, HMO, or Medicare to clarify your potential coverage and out-of-pocket costs. You don’t want any surprises if the costs of doctor’s visits for insertion and removal of sensors are, for example, not covered.

See more helpful articles:

Getting Started with a Continuous Glucose Monitor (CGM)

The Best Ways to Avoid High Blood Sugars

10 Keys to Controlling Your Blood Glucose