Introduction Cardiovascular autonomic neuropathy is one of the most common complications of diabetes mellitus type 1 (DM1), of which one of the first subclinical manifestations is changes in heart rate variability (HRV). covariance analysis was used to compare groups and ANOVA for repeated measures to compare the effects of the active orthostatic test. These data were adjusted for age, sex, ethnicity, body fat percentage and casual blood glucose, with a 5% significance level. Results The results suggested that diabetic children at buy AMG-458 rest present a decrease in SDNN (50.4 vs. 75.2), rMSSD (38.7 vs 57.6) and LF [ms2] (693.6 vs 1874.6). During the active orthostatic test the children in both groups demonstrated a reduction in SDNN, RMSSD and LF [ms2] compared to the resting position, and this response buy AMG-458 was less pronounced in the diabetic group. Conclusion We conclude that regardless of age, sex, ethnicity, body fat percentage and casual blood buy AMG-458 glucose, performing the active orthostatic test promoted increased sympathetic modulation and reduced parasympathetic modulation in both groups, and this response was less pronounced in diabetic children, who presented reduced overall variability and parasympathetic modulation. Introduction Diabetes mellitus (DM) is considered a serious public health problem due to an increase in the prevalence, morbidity and mortality in developed and developing countries . In childhood, DM type 1 (DM1) has been indicated as one of the most common endocrine diseases [2,3], and in the world it is estimated that there are over 500,000 children under 15 who present DM1, while Brazil has 31,000 registered cases of children diagnosed with this pathology . Diabetic autonomic neuropathy (DAN) is one of the most common complications of DM1 and can affect any organ system, however, in general, it initially affects the cardiovascular system, triggering cardiovascular autonomic neuropathy (CAN) [4C6]. In DM1 individuals, autonomic alterations resulting from CAN are diagnosed late, being discovered when the disease is already in advanced and irreversible stages , which aggravates the clinical condition and is associated with various complications and consequent increased mortality . One of the first sub-clinical manifestations of CAN can be alterations in heart rate variability (HRV) [3,4], a method that describes the oscillations of RR intervals between consecutive heartbeats, providing information on the autonomic nervous system (ANS) [7C9]. Studies indicate that diabetic children present HRV alterations characterized by reduction in buy AMG-458 overall variability and parasympathetic activity [10C16], however, these IRF5 studies do not consider factors that influence the autonomic changes such as sex , age , ethnicity , body fat percentage  and casual blood glucose . For a more complete analysis of the ANS, the association of analysis of HRV indices with the realization of autonomic testing can be an effective combination . These tests are based on the application of a stimulus and, sequentially, observation of the physiological response of the target organ to a known autonomic reflex, or by using drugs that interfere directly or indirectly in the activity of the ANS . One physiological autonomic test which is used is the orthostatic test [21,22], which promotes stimulus of ANS characterized by increased sympathetic modulation and vagal inhibition and can be performed actively or passively . The active orthostatic test is a simple assessment when compared to the passive orthostatic test and other autonomic tests, in addition to being a low-cost method . Despite its importance, few studies have evaluated autonomic modulation, associating HRV with autonomic tests in this population. After searching the relevant technical literature, only one study was found using the active orthostatic test in diabetic children . In this study it was observed that the HRV indices followed a pattern of sympathetic activation and vagal withdrawal during the realization of the active orthostatic test, however these changes were similar in DM1 and healthy individuals . In this context, studying the analysis of HRV associated with autonomic tests may help in better understanding the influence of DM1 on.