Cardiac Autonomic Dysfunction in Type 2 Diabetes – Effect of Hyperglycemia and Disease Duration

Abstract

Heart rate variability (HRV) is reduced in diabetes mellitus (DM) patients, suggesting dysfunction of cardiac autonomic regulation and an increased risk for cardiac events. The aim of this paper was to examine the associations of blood glucose level (BGL), glycated hemoglobin (HbA1c), and duration of diabetes with cardiac autonomic regulation assessed by HRV analysis. Resting electrocardiogram (ECG), recorded over 20 min in supine position, and clinical measurements of 189 healthy controls and 93 type 2 DM (T2DM) patients were analyzed. HRV was assessed using several time-domain, frequency-domain, and non-linear methods. HRV parameters showed a clear difference between healthy controls and T2DM patients. Hyperglycemia was associated with increase in mean heart rate and decrease in HRV, indicated by negative correlations of BGL and HbA1c with mean RR interval and most of the HRV parameters. Duration of diabetes was strongly associated with decrease in HRV, the most significant decrease in HRV was found within the first 5–10 years of the disease. In conclusion, elevated blood glucose levels have an unfavorable effect on cardiac autonomic function and this effect is pronounced in long-term T2DM patients. The most significant decrease in HRV related to diabetes and thus presence of autonomic neuropathy was observed within the first 5–10 years of disease progression.

Data-analytically derived flexible HbA1c thresholds for type 2 diabetes mellitus diagnostic

“…[35] We assume that the same standard to how it is done applied in both studies. [15,16] IHR Approximate Entropy is not notionally different from IHR Sample Entropy, and so qualitatively same result is expected. It appears though that IHR Sample Entropy is much worse on its own in determining T2DM outcomes, as seen from Table 6, which correlates with other results obtained for CAN diagnostic in the DiScRi space.…”

“…Similarly, there is a study in the DiScRi space where T2DM subjects are compared to healthy controls, and where the cholesterol profiles were examined, even though the study is seemingly unrelated, concerned with CAN. [15] The use of unspecified anti-cholesterol medicines was there higher by T2DM patients (68%) than by healthy subjects (25%). Accordingly, the cholesterol levels were down in the T2DM cohort comparing to controls as follows: LDL by 23%, TC by 14%, and HDL by 14%.…”

“…Indeed, hyperglycaemia causes increased HR in observations. [15] Is this effect, though, discernable in ECG unaided? The obvious choice of feature to examine first is the QRS complex, a waveform so denoted -the main impulse, distinct on a normal ECG.…”

“…The utility of the IHR Sample Entropy is also acknowledged in another study concerned with CAN diagnostic in a mixed population of T2DM subjects and healthy controls. [15] The analysis was performed on a sample of DiScRi data, and the first study may as well have contributed to project. However, there is a number of ways of calculating the quantity.…”

“…[12] This may explain that varied results are obtained world-wide for HbA1c as a clinical marker in T2DM diagnostic. [8] Beyond protein glycation, DM progression is linked to markers of endothelial [13,14] and autonomic nervous system (ANS) dysfunction, [15,16] inflammatory [17,18] and oxidative stress [19,20] biomarkers. Recent literature reports that presence of 8-hydroxy-2'-deoxy-guanosine (8-OHdG) in blood or urine samples is indicative of oxidative stress and deoxyribonucleic acid (DNA) damage due to minor increases in the PG level.…”