The correlations of glycated hemoglobin and carbohydrate metabolism parameters with heart rate variability in apparently healthy sedentary young male subjects

Abstract

Introduction

Sedentary lifestyle is a major risk factor for diabetes, cardiovascular and many other age-related diseases. Heart rate variability (HRV) reflects the function of regulatory systems of internal organs and may sensitively indicate early metabolic disturbances. We hypothesize that quantitative and qualitative changes of HRV in young subjects may reflect early metabolic derangements responsible for further development of clinically significant disease.

Aim

The aim of our study was to determine whether the parameters of carbohydrate metabolism (fasting blood glucose, HBA _1c and surrogate insulin sensitivity/resistance indices) correlate with anthropometric data and HRV.

Methods

The study group consisted of 30 healthy sedentary male subjects aged 20–40, nonsmokers, mainly office and research employees, medical staff and students. Athletes, actively training more than one hour per week, severely obese and men of physical work were excluded from the study. HRV parameters were derived from short term ECG records (five minutes intervals) in supine position and during orthostatic test. Anthropometric data included height, weight, body mass index (BMI), age and body composition (estimation by bioelectric impedance method). The fasting blood glucose, insulin and C-peptide, homeostatic model assessment (HOMA-IR) index and glycated hemoglobin (HbA _1c) were evaluated. Linear correlation coefficient ( r) was calculated using Statistica 10.0 software.

Results and discussion

HOMA-IR index correlated positively with body weight, visceral fat and BMI ( p=0.047, 0.027 and 0.017 respectively). In supine position pNN50 positively correlated with glucose/insulin ratio ( p=0.011) and heart rate with HOMA-IR ( p=0.006). In orthostatic test negative correlations of HBA _1c with standard deviation, total and low frequency power were determined ( p=0.034, 0.400 and 0.403 respectively), which indicates a gradual worsening of functional capacity of cardiovascular system with low-grade increase (under the conventional threshold) of HBA _1c.

Conclusions

In apparently healthy sedentary subjects HRV reduction correlates with the age advancement, subclinical deteriorations of carbohydrate metabolism and excessive fat accumulation.

Graphical abstract

Highlights

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  Apparently healthy sedentary young male subjects were enrolled in the study.

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  HRV negatively correlates with age, BMI, visceral fat and insulin resistance.

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  Glycated hemoglobin negatively correlates with HRV parameters in orthostatic test.

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  Changes of HRV may reflect subclinical metabolic deteriorations in sedentary subjects.