Abstract:Objective To investigate the value of heart rate deceleration capacity (DC) in assessing the autonomic nervous system dysfunction in juveniles with metabolic syndrome (MS). Methods Totally 100 juvenile aged 10 to 16 years who were first time diagnosed as MS from January 2014 to May 2015 were involved as the observation group, meanwhile 100 healthy volunteers whose sex and age were matched were involved as the control group. The DC and heart rate variability (HRV) were detected in all cases. Children in the observation group were further divided into 3 subgroups, the cases with DC ≥ 4.5 ms were included as low-risk group, those with DC of 2.6- 4.5 ms were included as mid-risk group, and those with DC ≤ 2.5 ms were included as high-risk group. All cases were followed up for at least 24 months, the changes in fasting blood glucose (FBG), fasting insulin (FINS), highdensity lipoprotein cholesterol (HDL-C), triglyceride (TG), total cholesterol (TC), serum uric acid (UA) and blood calcium were compared. Results DC and HRV indexes in the observation group were much lower than those in the control group (P < 0.05). There were positive correlations between DC and HRV indexes (P < 0.05). After 24 months of follow-up, FBG, FINS, TG, TC and UA in the high-risk group were much higher than those in the mid risk group and the low-risk group (P < 0.05). Conclusions Juveniles with MS are basically accompanied by abnormal DC decrease, and the change is associated with the abnormality of HRV related indicators. The abnormal autonomic nervous function is more severe in the patients with DC ≤ 2.5 ms.