Page 137 - Glucose Monitoring Devices

138 CHAPTER 7 Clinical impact of CGM use

Benefits of CGM
Operational advantage
As an alternative point-of-care modality to SMBG, CGM conveniently provides
instant access to real-time glucose levels, the trajectory of glucose levels, the
rate of change of glycemia, and a visual indication of time spent in a target gly-
cemic range. The operational process necessary to obtain a capillary glucose
measurement using conventional dry-reagent strips can be time consuming and
inconvenient, particularly in the working environment. Many CGM systems uti-
lize a familiar and universally adopted technology such as the smartphone to
immediately present data and overcome potential operational barriers and stigma
attached to using capillary glucose testing kits. Automated CGM measurements
uploaded directly to the user’s smartphone or proprietary receiver make moni-
toring glucose levels intuitive, and aid individuals that find SMBG difficult to
remember. The increasing life span of current sensors exceeding beyond
1 week, and one of the latest sensors in the market requiring no calibration, further
contributes toward reducing the burden of skin pricking associated with conven-
tional SMBG.

Direction, pattern and trends, investigative tool
Planning and undertaking events with a significant glycemic impact can be chal-
lenging when uncertain about the imminent direction or trajectory of glucose levels.
Most CGM systems can inform users if glucose levels are rising, falling, or steady
and, in turn, assist insulin dose decisions particularly when planning meals or phys-
ical activity.
Using CGM offers unprecedented insight into a full 24-h glucose profile and
allows users and healthcare professionals the opportunity to contextualize glucose
excursions and glycemic variability. The glycemic load and response to meals
represent the biggest influence on blood glucose levels and often demonstrate
significant variability within and between individuals. Applying CGM to individ-
ually characterize the glycemic impact of meal types helps with calculating accu-
rate insulin-to-carbohydrate ratios and the consideration of using extended insulin
boluses. Overnight, people often report significant variation in blood glucose
levels at a time when performing frequent SMBG is limited by sleep. The
dawn phenomenon best illustrates this and describes an early morning circadian
elevation in hormones responsible for an increase in fasting glucose in a popula-
tion of individuals with impaired b-cell function [34e37]. Different from the
Somogyi effect, it is not preceded by iatrogenic hypoglycemia; however, both
can be responsible for unpredictable overnight hyperglycemia. Overnight CGM
usefully illustrates this glycemic pattern in individuals struggling with fasting
hyperglycemia and assists in compensatory basal insulin dose adjustments.
Extended use of CGM ultimately facilitates the fine-tuning of glycemic control
by lifestyle and therapeutic changes in response to real-time and retrospectively
identified temporal and behavioral trends.