Poorly controlled blood sugar tied to lower heart rate variability in diabetes patients: Study

"These data strongly suggest that cardiac autonomic dysfunction is caused by increased levels of blood sugar," the researchers wrote. Cardiac autonomic dysfunction is a complication of diabetes that carries an about fivefold increased risk of mortality in adults.

The amount by which HRV was lower in diabetes patients with TIR < 70% (compared to those with TIR > 70%) was about 2/3 in both the time and frequency domains.

Autonomic neuropathy occurs commonly as a long-term complication of diabetes and can be diagnosed based on HRV, calculated from electrocardiogram (ECG) recordings. Heart rate variability is the fluctuation in the time interval between adjacent heartbeats.

Limited research has been done on HRV using real-time ECG and ambulatory glucose monitoring in diabetes patients. Sung Il Im, Kosin University College of Medicine, Busan, Republic of Korea, and colleagues, therefore, aimed to investigate real-time HRV according to ambulatory glucose levels in diabetic patients.

For this purpose, the researchers included 43 patients (66.3 ± 7.5 years) with diabetes mellitus. They underwent continuous real-time ECG monitoring (225.7 ± 107.3 h) for HRV and ambulatory glucose monitoring using a remote monitoring system. HRV was compared according to the ambulatory glucose profile. Data analysis was done according to the target in the glucose range (TIR).

The study revealed the following findings:

• There were no significant differences in the baseline characteristics of the patients according to the TIR.
• During monitoring, ECG and ambulatory glucose levels (a total of 15,090 times) were checked simultaneously for all patients.
• Both time- and frequency-domain HRVs were lower when the patients had poorly controlled glucose levels (TIR < 70%) compared with well-controlled glucose levels (TIR > 70%).
• Heart and respiratory rates increased with real-time glucose levels.

"Our results support the concept that cardiac autonomic dysfunction occurs when poorly controlled glucose levels are measured in real-time before checking long-term glucose level predictors such as C-peptide levels and HbA1c may play a role in the development of cardiovascular diseases earlier in the course of type 2 diabetes," the researchers wrote.

"These data strongly indicate that cardiac autonomic dysfunction is caused by increased blood sugar levels," they concluded.

Reference:

Im, S. I., Kim, S. J., Bae, S. H., Kim, B. J., Heo, J. H., Kwon, S. K., Cho, S. P., Shim, H., Park, J. H., Kim, H. S., & Oak, C. H. (2023). Real-time heart rate variability according to ambulatory glucose profile in patients with diabetes mellitus. Frontiers in Cardiovascular Medicine, 10, 1249709. https://doi.org/10.3389/fcvm.2023.1249709