ABSTRACT
Background: Heart rate variability analysis provides quantitative information about vagal and sympathetic modulation of cardiac function. Aim: To analyze the relationship between heart rate variability and insulin resistance in obese patients. Material and Methods: Male participants were studied, divided in 10 obese subjects aged 27 ± 2 years with a body mass index (BMI) of 31.2 ± 1.3 kg/m², 15 overweight subjects aged 24 ± 3 years with a BMI of 26.7 ± 1.5 kg/m² and 14 normal weight subjects aged 21 ± 2 years with a BMI of 22.5 ± 1.3 kg/m². Resting heart rate variability was measured in a period of 5 minutes. A spectral analysis was done measuring the low frequency/high frequency ratio (LF/HF). A non- linear analysis was carried out measuring the standard deviation of the instantaneous variation of RR intervals (SD1) and α-1 or a fractal analysis of RR interval complexity. A fasting blood sample was obtained to measure blood glucose and insulin and calculate the homeostasis model assessment for insulin resistance (HOMA-IR). Results: Among obese subjects HOMA-IR, LF/HF, α-1 and SD1 values were 2.6 ± 2.1, 2.4 ± 1.8, 1.2 ± 0.06 and 22.5 ± 10 respectively. The figures for normal weight subjects were 0.5 ± 0.1, 1.3 ± 0.2, 0.9 ± 0.3 and 26 ± 7.8 respectively. Conclusions: There is an association between spectral and fractal values of heart rate variability and HOMA-IR. These results may indicate a predominance of sympathetic control of heart rate among obese subjects.