IDF21-0409 Hypoglycemia and heart rate variability: synchronous detection by Holter and continuous glucose monitors

Abstract

Background: Hypoglycemia is a notorious diabetic side effect leading to unwanted major vascular events and sudden cardiac death due to change in autonomic cardiac function. Previous studies have reported electrocardiographic (ECG) abnormalities such as QT interval prolongation in patients with hypoglycemia, so did heart rate variability (HRV). Aim: To document ECG and HRV changes during hypoglycemia and expect to establish a portable device to early detect hypoglycemia in the future. Method: Seventeen participants including ten poor controlled type 2 diabetes, six type 1 diabetes and one Latent autoimmune diabetes in adults (LADA) were enrolled in this study. There were six males and eleven females, aged from 37 to 77 (mean 50.3 ± 12.0) years old, with self-reported duration of diabetes from 6 to 33 (mean 20.8 ± 8.7) years. The mean HbA1c was 8.3 ± 1.4 % on the time of the examination. We used Holter- electrocardiogram (VitalSigns) and continuous glucose monitor (Medtronic) to record ECG waveform, heart rate variability and glucose level with synchronization of time for a duration of seven days. Results: Two of the seventeen participants did not experience hypoglycemia (≦70 mg/dL). The other participants who experienced hypoglycemia revealed, as a whole, a trend of correlation between blood glucose, corrected QT Interval (QTc), and HRV. When the participants experienced hypoglycemia were sub-divided into response and non-response groups according to the appearance of QTc prolongation, significant difference of age was found between two groups, most of them were type 1 diabetic patients. Among 90 events of hypoglycemia, 56 events (62%) presented with increased heart rate and/or Low Frequency/ High Frequency (LF/HF) ratio and /or decreased Root Mean Square of the Successive Differences (RMSSD). Besides, there were a trend of difference of glucose nadir, HRV include heart rate, RMSSD and LF/HF ratio between two groups. Discussion: In this study, Type 1 DM patient and younger age were easier to have QT interval prolongation during hypoglycemia. Besides, increased LF/HF ratio may represent that these group of patients have better regulation of autonomic nervous system. Heart rate variability can be seen during hypoglycemic events in both type 1 and type 2 diabetic patients especially in the response group.