Relationship between spectral indicators of heart rate variability and fasting glucose level in healthy persons and elderly patients with discirculatory atherosclerotic encephalopathy
Authors: Korkushko O. V. , Chyzhova V. P. , Kuznietsov V. V. , Apykhtin K. O. , Koshel N. M. , Cherska M. S. , Proskura T. O. , Samots I. A. , Naumchuk N. S. 
Published: April 2021

Objective — to establish  the peculiarities and relationship of spectral indicators of heart rate variability (HRV), fasting glucose level and lipid profile indicators in practically healthy persons and in elderly patients with dyscirculatory atherosclerotic encephalopathy (DEP).
Materials and methods. The study involved 77 subjects of various age, who were divided into two groups: group 1 consisted  of apparently  healthy persons (19  subjects of middle age and 27 elderly subjects) and group 2 that included patients with DAP manifestations (15 subjects of middle age and 16 elderly persons). In the groups of elderly persons, the subgroups were extracted based on the fasting glucose levels: lower than 6.1 mmol/l and 6.1 mmol/l. The measurements of systolic and diastolic blood pressure were performed in a sitting position after at least 10 min of rest. Plasma glucose levels were determined by a standard glucoseoxidase method, lipid profile was determined by using the automatic analyzer. To assess the risk of cardiovascular disease development, calculations were performed for the indices of the cardiovascular risk: Castelli index and Boizel index. All patients with DEP manifestations underwent 24‑hour Holter ECG monitoring, and healthy people underwent 5 min ECG.
Results. The incidence of fasting hyperglycemia in patients with 1 — 2 stage DEP manifestations was in 3.4 times higher (p < 0.05) vs healthy subjects of the same age. The significant correlation has been reveled between age and HDL‑C (r = 0.47, р < 0.05), atherogenic index (r = –0.40, р < 0.05), heart rate (r = –0.45, р < 0.05), Castelli index (r = –0.40, р < 0.05), Boizel index (r = –0.31, р < 0.05), heart rate (r = –0.45, р < 0.05). Moreover, correlation has been established between Boizel index and heart rate (r = +0.44, р < 0.05), heart rate and LF/HF (r = +0.57, р < 0.05), between TG and heart rate (r = +0.43, р < 0.05), LF/HF (r = +0.53, р < 0.05) and between levels of very low density lipoprotein cholesterol and heart rate (r = +0.44 р < 0.05), LF/HF (r = +0.53, р < 0. 05). It has been established that hyperglycemia and dyslipidemia significantly affected spectral heart rate variability indices in patients with encephalopathy manifestations.
Conclusions. With ageing, the frequency of fasting hyperglycemia in patients with 1 — 2 stage DEP manifestations was significantly higher in 3.4 times in comparison with practically healthy individuals of the same age. In the group of practically healthy persons over 60 years old, the tendency has been revealed towards a decrease in the spectral parameters of HRV LF and HF, which indicates HRV decrease. With the development of 1 — 2 stages DEP, even in the middle age, a significant decrease in the value of HF (parasympathetic influence) and a significant increase in the value of LF (sympathetic activity) were revealed. In elderly people with signs of 1 — 2 stage DEP with normoglycemia and fasting hyperglycemia against the background of dyslipidemia, the sympathetic link of the autonomic nervous system is activated, accompanied by an increase in the index of vascular complications. In patients with 1 — 2 stages DEP and fasting hyperglycemia, this tendency was even more pronounced. This fact can serve as confirmation that in the development of pre‑diabetic disorders (fasting hyperglycemia) one of the pathogenic mechanisms is the violation of the central regulatory mechanisms, which in turn leads to the violation of the autonomic balance with the prevalence of sympathicotonia, and a decrease in the parasympathetic effect on the heart, which leads to development of autonomous cardiac neuropathy.