Page 150 - Glucose Monitoring Devices

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Further utility of CGM

Improved glycemic control outcomes extended to significantly lower measures of
glucose variability and better Diabetes Treatment Satisfaction Questionnaire scores
[68]. In T2DM populations, flash glucose monitoring has been shown to significantly
reduce hypoglycemia (<70 mg/dL, <3.9 mmol/L) risk by 55% with reduced SMBG
frequency [69]. Selective application of flash monitoring based on these outcomes
would place individuals at high risk of hypoglycemia as the most likely to benefit.
The I HART CGM study compared the efficacy of flash glucose monitoring and
CGM at reducing hypoglycemia in a prospective parallel-group study among T1DM
adults at high risk [70]. Following a 2-week run with blinded CGM, participants
were randomized to either real-time CGM or flash monitoring for 8 weeks with
an option for all participants to continue real-time CGM for an additional 8 weeks.
The group switching from flash monitoring to real-time CGM showed a significant
reduction in time spent in hypoglycemia (<54 mg/dL, <3.0 mmol/L) and increased
time in target range (<70e180 mg/dL, 3.9e10 mmol/L) [70]. In contrast, no signif-
icant changes were observed in the participants that remained on real-time CGM
suggesting superiority when addressing risk in T1DM adults vulnerable to
hypoglycemia.
The Abbot Freestyle Libre is currently the only available flash glucose moni-
toring system available. Both the sensor and transmitter are housed in a single
disc-shaped unit sited in the upper arm. A MARD of 10% delivers accuracy nearly
comparable to available CGMs; however, false-positive hypoglycemia readings sug-
gest a decline in sensor accuracy in the low glucose range. The transmission of data
is currently limited to the proprietary Freestyle Libre receiver and smartphones with
the Freestyle Librelink App. The soon to be available next-generation FreeStyle
Libre 2 system builds on the success of its predecessor by introducing an optional
customizable alarm feature for hypoglycemia, hyperglycemia, and Bluetooth signal
loss. This inclusion overcomes a significant limitation of flash glucose monitoring
and makes strides toward bridging the gap with CGM.

Further utility of CGM
Combining technology
The sensor-augmented pump (SAP) combines CGM and a CSII pump to deliver
real-time glucose readings to the pump interface. This provides convenience and
continuous blood glucose feedback to support insulin dose adjustment. The ability
to automatically suspend insulin pump delivery once glucose levels reach a precon-
figured threshold “low glucose or threshold-suspend” is a feature adopted by SAP
systems to help mitigate hypoglycemia risk and bypass user error when responding
to CGM alarm notifications. Sensor-augmented pumps and low glucose suspend
have been shown to successfully reduce HbA1c and overnight hypoglycemia. A
1-year multicenter randomized control trial comparing SAP to MDI demonstrated
a weight neutral significant reduction in HbA1c, 7.5% versus 8.1% (P < .001) [71].