Page 110 - Glucose Monitoring Devices

CHAPTER

6
CGM sensor technology

1
Andrew DeHennis, PhD , Mark Mortellaro, PhD 2
1
Sr. Director of Engineering, R&D, Product Development Senseonics Incorporated, Germantown,
2
MD, United States; Director of Chemistry, Senseonics Incorporated, Germantown, MD,
United States

Introduction
Although self-monitoring of blood glucose has been an important tool for managing
diabetes for several decades, this method has some significant limitations. It requires
patients to prick their fingers using a lancing device to obtain a small blood sample,
then apply the drop of blood onto a reagent strip, which is then read by a glucometer.
Patients must do this multiple times a day, then analyze the readings to check their
treatment or adjust their diet, insulin, antidiabetic medication, or exercise to keep
their glucose levels within the target. Patients need to maintain a regular regimen
of self-testing for self-management to be effective. Additionally, because the self-
glucose checks are performed at only a few times during the day and capture only
the blood glucose reading at that specific time, high and low spikes in blood glucose
that can happen at any time of the day or night can be missed, as shown in Fig. 6.1.
The identification and analysis of trends in blood glucose data difficult.
To improve the management of diabetes, Continuous Glucose Monitoring
(CGM) systems have been developed, which incorporate advances in microelec-
tronics, implantable materials, and wireless technology to provide an accurate
long-term picture of glucose levels in both real time and over extended periods.
This insight into glycemic variability enables users and physicians to make adjust-
ments to their treatments and medications. Applications for the use of CGM systems
are covered in [48].
This chapter describes the CGM technology and system components that are
overviewed in Fig. 6.2 to enable CGM, focusing both on technology in systems
that are currently available and systems being developed for future platforms. A dis-
cussion of performance factors will include accuracy metrics, sensor life/stability,
and wireless connectivity of systems. A review of patient usability factors will
include alerts and alarms, trends, plotting, and smartphone apps.

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