Low insulin sensitivity and development of type 2 diabetes might be the consequence of cardiovascular autonomic dysfunction. Cardiovascular autonomic function may be assessed noninvasively by the analysis of the heart rate variability... more
Low insulin sensitivity and development of type 2 diabetes might be the consequence of cardiovascular autonomic dysfunction. Cardiovascular autonomic function may be assessed noninvasively by the analysis of the heart rate variability (HRV) using time-domain, frequency-domain and non-linear methods. Time-domain and frequency-domain methods have been extensively used in subjects with metabolic syndrome but non-linear methods are not commonly employed. In this paper, we use non-linear and time-and frequency-domain methods to analyze the HRV of people that underwent a 2-hour 5-sample oral glucose tolerance test (OGTT). The main goal of this work is to find clinical indicators that could relate insulin sensitivity with HRV parameters in subjects with metabolic syndrome, marathoners and sedentaries people. Results show that, compared with marathoners, people with metabolic syndrome have lower rMSSD, SDNN, SD1 and SD2 during 5-sample OGTT. In LF and LF/HF ratio, marathoners presented increased values and people with metabolic syndrome reduced values respect to sedentaries, showing a parasympathetic activity decreased in people wih metabolic syndrome, but increased in marathoners. Differences found in HRV parameter along the OGTT in people wih metabolic syndrome and marathoners suggest that changes in their cardiac autonomic function are due to sudden increases of insulin levels. OGTT altered HRV parameters in people wih metabolic syndrome, marathoners and sedentaries subjects. HRV was reduced in metabolic syndrome subjects and increased in marathoners comparing with sedentary subjects.