Geometric indexes of heart rate of variability identifies autonomic alterations in young patients with type 1 diabetes mellitus

Abstract

Objectives: To compare autonomic modulation in young patients with type 1 diabetes mellitus (DM1) (n=20) and healthy control subjects (n=23) using geometric indexes of heart rate variability (HRV) associated with linear domains of time and frequency; and to verify correlations between geometric indexes and those obtained by the time and the frequency domain of diabetic individuals. Methods: Heart rate was recorded as beat-to-beat with subjects supine for 30 min. The following indexes were calculated: RRtri, TINN, Poincare plot, SD1, SD2, SD1/SD2, RMSSD, SDNN, LF and HF (ms²/un) and LF/HF. Visual analysis of the Poincare plot was also performed. Independent Student’s t test or Mann-Whitney test, and Spearman’s correlation test or Pearson’s correlation test were used for statistical analysis. Results: Significantly lower values of SD1, SD2, RRtri, RMSSD, SDNN, and LF and HF in ms² were observed in patients with DM1 compared with healthy subjects. Conclusion: The Poincare plot showed less dispersion of RR intervals for the DM1 group. Strong correlations were observed with the geometric indexes with the time domain and frequency indexes.