Page 126 - Glucose Monitoring Devices

Commercial systems 127

implanted sensors communicate wirelessly with a transmitter worn over the sensor,
and due to the nature of the sensor being placed completely under the skin, the trans-
mitter can be removed and replaced without disturbing the sensor.
Four companies are currently making commercially available continuous
glucose monitors. Dexcom, Abbott, Medtronic, and Senseonics all have products
available in both the United States and Europe. The next sections further detail
the features of their available CGM systems.

Abbott Freestyle Libre flash glucose monitor
The Freestyle Libre flash glucose monitor is a self-inserted transcutaneous CGM
that is indicated for persons 18 years and older in the United States, and for ages
4 and older outside the United States. The Abbott Freestyle sensor uses an adhesive
that is acrylic-based and worn for the life of the sensor, up to 14 days. Flash glucose
monitoring is slightly different from CGM, as it requires the user to “flash” or scan
the reader over the sensor to wirelessly collect and display a glucose reading and
trend arrow. The system requires a scan every 8 h and there is a 1 h warm-up period
at the start of each 14-day sensor session. Fingerstick blood glucose monitoring is
not required except for situation labeled in the IFU such as during the first 12 h of
wear, if symptoms do not match values, or other reasons discussed in the labeling.
Depending upon the Libre product (e.g., a product marketed in the United States vs.
other geographies), the system may or may not offer optional high and low glucose
alerts.
The system is inserted by the user with the aid of a disposable, spring-loaded in-
jection insertion device. The sensor and transmitter are combined in a single unit,
which is worn at the back of the user’s arm. Because the sensor and transmitter
are combined, when removed, the user must replace it with a new unit. The con-
nected app on the reader or smartphone provides glucose information.

Dexcom G6 CGM
The Dexcom G6 is a self-inserted transcutaneous CGM for ages 2 and older. Similar
to the Freestyle Libre, the Dexcom G6 sensor is affixed to the body using a patch
adhesive that is acrylic-based, and worn for the life of the sensor, up to 10 days.
It is inserted using an injector device that deploys the sensor transcutaneous and
enables connections to the attachable transmitter. The device needs to be unlocked
and the sensor is loaded into the insertion device. Open the needle by removing the
needle guard. Put the insertion tool on the patient’s skin while ensuring that the skin
is flat before pressing a button to insert the sensor [35]. Fingerstick blood glucose
monitoring is not required unless CGM values do not match symptoms and other
reasons contained in the labeling. The Dexcom G6 does not require calibration
unless the sensor code is not entered, which the user can enter optionally. The
warm-up period is 2 h for each 10-day sensor session. The G6 provides high, low,
rate of change and predictive urgent low alerts.
Similar to the Freestyle Libre, the Dexcom G6 is indicated for nonadjunctive use,
allowing the user to determine what treatment decisions to make without a