Page 151 - Glucose Monitoring Devices

152 CHAPTER 7 Clinical impact of CGM use

The ASPIRE trial showed the impact of the low glucose suspend feature in T1DM
adults with documented nocturnal hypoglycemia by successfully demonstrating a
32% reduction in the frequency of nocturnal hypoglycemia and a 38% lower
mean area under the curve when combining threshold suspend alongside SAP
compared with SAP alone [72]. Successful integration of diabetes technologies
is considered a crucial step toward developing a fully automated closed-loop
insulin delivery system “artificial pancreas.” Closed-loop studies have yielded
significant improvements in measures of glucose control, especially overnight.
These include, increased percentage time in range, and reduced time spent in
hypo and hyperglycaemia [72a]. Hybrid closed-loop systems leave prandial insulin
bolus delivery in the hands of the user and apply automated insulin delivery
throughout the rest of the day. As part of the Medtronic ecosystem, combining
the Guardian Connect CGMs and the MiniMed 670G pump takes advantage of
Medtronic’s self-adjusting insulin delivery technology (Medtronic SmartGuard).
Functioning as a hybrid closed-loop artificial pancreas, SmartGuard is capable
of 5-min dose titration against CGM-derived glucose levels.

Inpatient CGM
Worsening glucose control and hyperglycemia are commonly seen during intercur-
rent illness in diabetes. Diabetes care in the critically unwell was previously focused
on achieving tighter glucose control and preventing possible effects of stress-
induced hyperglycemia [73]. Studies have since produced conflicting evidence
regarding the impact of critical illness-induced stress hyperglycemia with some
studies conversely associating tight glycemic control with an increased risk of
mortality [74]. As a result, critical care strategies have evolved to target moderate
glycemic control while considering the clinical impact of premorbid HbA1c, relative
hypoglycemia, and glucose variability. Despite many intensive care units (ICU)
adopting intravenous insulin infusion and frequent capillary glucose monitoring to
achieve predetermined glucose parameters, CGM use has not successfully crossed
over to inpatient settings. A review of inpatient CGM clinical trials showed no addi-
tional glycemic control benefit when CGM is applied to ICU patients already under-
going frequent CBG for intravenous insulin infusion titration [75]. However, it must
be stated that ICU CGM outcomes are limited by the small number of available
studies and the significant heterogeneity with regards to the severity of illness,
type of diabetes, and choice of CGM among study participants. Outside of ICU,
CGM outcomes fall closer in line with outpatient results with superior detection
of hypoglycemia compared to CBG [75]. Further work is required comparing
CGM outcomes in T1DM and T2DM populations at varying levels of critical care
dependency.

Summary

In an endeavor to reduce the morbidity and mortality associated with diabetes-
related complications, CGM successfully facilitates frequent glucose monitoring