Use of CGM Can Help Diagnose Impaired Hypoglycemia Awareness

People who have type 1 diabetes (T1D) can develop a condition called impaired hypoglycemia awareness, in which they do not sense that their blood sugar is falling to the point that they could need medical attention. Hypoglycemia is defined as having a blood glucose level <70 mg/dL; very low blood glucose, or <54 mg/dL, is dangerous, and the person is in need of immediate attention.

Normally, a person experiencing hypoglycemia has tell-tale physical symptoms, such as hunger, paleness, sweating, or irritability, which can be addressed before they progress to more serious problems, such a mental confusion or loss of consciousness.

But the person who lacks hypoglycemia awareness may not have those physical signals, and the risk of hypoglycemia is especially high during sleep. Mild cases may also go unnoticed. Over many years, chronic glycemic variability can cause complications, so use of modern tools, including continuous glucose monitoring (CGM), has helped patients and physicians more closely track blood glucose levels, to identify those who lack awareness of hypoglycemia.

Researchers from Ege University in Turkey sought to use a professional CGM model for pediatric patients; first, to identify those who had impaired hypoglycemia awareness, and second, to put those with impaired awareness through a training program that would help them better identify symptoms. Final results were published this week in the Journal of Clinical Research in Pediatric Endocrinology.

Forty children and teens who had lived with T1D at least 5 years were identified (3 later dropped out of the study), and all were asked if they had periods of hypoglycemia; possible answers were “yes,” “no,” and “sometimes.” Study participants were provided with a professional CGM system and sensor placement, and parents and patients were asked to record results from 4 finger stick readings per day, along with insulin doses, meals, exercise, and symptoms of hypoglycemia.

After 6 days, the researchers downloaded the CGM data and compared it with recorded glycated hemoglobin (A1C) in the patients’ medical records. New A1C measures were recorded. Patients with impaired hypoglycemia awareness went a training program that included safe exercise management and were seen weekly for 3 months; at that point, CGM was reapplied.

Results. At the initial CGM reading, 9 patients, including 6 females, had impaired hypoglycemia awareness (24.3%). These patients had blood glucose of <70 mg/dL for 11.44 hours (± 5.12 hours) per day while patients who had awareness had hypoglycemia for 1.93 hours (± 2.23 hours) per day. Seven were using multiple daily injections and 2 were using an insulin pump. There was no significant correlation between the answers the patients filled out on questionnaire about their sensation of symptoms and the true presence of impaired awareness as recorded by the CGM.

After 3 months of structured education on impaired hypoglycemia awareness, the patients with impaired awareness had reduced their time in hypoglycemia to 4.44 hours (± 3.78 hours).

The authors noted the significant improvement achieved in a relatively short period of time, given the increased attention being paid to time in range. “Avoiding hypoglycemia for 3 weeks is sufficient for the abolition of [impaired hypoglycemia awareness] and partial restoration of the adrenal response to hypoglycemia,” they wrote.

Reference

Demir G, Ozen S, Cetin H, Darcan S, Goksen D. Effect of education on impaired hypoglycemia awareness and glycemic variability in children and adolescents with type 1 diabetes mellitus. J Clin Res Pediatr Endocrinol. 2019;11(2):189-195. DOI: 10.4274/jcrpe.galenos.2019.2019.0009.