[Heart rate variability and insulin resistance among obese males]

Heart rate variability analysis provides quantitative information about vagal and sympathetic modulation of cardiac function.

To analyze the relationship between heart rate variability and insulin resistance in obese patients.

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).

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.

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.