Page 268 - Glucose Monitoring Devices

CHAPTER

Predictive low glucose

suspend systems 14

1
Gregory P. Forlenza, MD , Laya Ekhlaspour, MD 2
1
Assistant Professor, Barbara Davis Center, University of Colorado Denver, Aurora, CO, United
2
States; Instructor, Pediatric Endocrinology, Stanford University, Palo Alto, CA, United States
Introduction

Hypoglycemia and fear of hypoglycemia have long been the major limiters to
improved glycemic control via reduced hemoglobin A1c (HbA1c) for patients
with type 1 diabetes (T1D). The Diabetes Control and Complications Trial famously
highlighted the tradeoff between improved HbA1c and increased incidence of severe
hypoglycemia [1e3]. For decades, the assumption among clinicians and patients
had been that one must endure a certain amount of hypoglycemia to have adequate
glycemic control. Without commercially available and reliable continuous glucose
monitoring (CGM) systems, hypoglycemia was generally identified solely by symp-
toms among those without hypoglycemia unawareness. Other identification and
potential prevention was achieved via routine scheduled self-monitoring of blood
glucose (SMBG) testing. This approach created burden and anxiety especially
during the overnight period when symptoms of hypoglycemia would not be present.
The physiology around hypoglycemia in patients with T1D is a well-studied
phenomenon. The normal physiological response to hypoglycemia involves the
shutoff of endogenous insulin production followed by counterregulation with the
release of glucagon, cortisol, epinephrine, norepinephrine, and growth hormone
[4]. In T1D, the counterregulatory response can become altered, likely due to
repeated exposure to hypoglycemia [5]. In severe cases, hypoglycemia regulation
can become so disrupted that patients experience hypoglycemia unawareness
contributing to a viscous cycle of recurrent severe hypoglycemia and decreased
hypoglycemia awareness [6]. Hypoglycemia responsiveness is also inherently
impaired during sleep as has been documented by decreased epinephrine and
increased arousal threshold in some studies [7,8].
Ingrowingchildren,hypoglycemiadparticularlyrecurrentseverehypoglycemiad
can negatively impact neurocognitive development. A negative impact on memory,
learning, intelligence, and verbal fluency has been documented in T1D children with
recurrent severe hypoglycemia compared to T1D children who do not experience
severe hypoglycemia [9]. Similarly, recurrent severe hypoglycemia has been docu-
mented to negatively impact spatial memory, particularly in young children [10].
Both electroencephalogram and magnetic resonance imaging have demonstrated

Glucose Monitoring Devices. https://doi.org/10.1016/B978-0-12-816714-4.00014-4 275
Copyright © 2020 Elsevier Inc. All rights reserved.