Heart rate variability and vibration perception threshold in type 2 diabetes mellitus

The aim of the study was to compare heart rate variability (HRV) and vibration perception threshold (VPT) of patients with type 2 diabetes mellitus (T2DM) with control. The study was conducted on 60 patients with T2DM and 30 controls. The short term HRV and VPT were assessed in the both groups. All the time domain measures, SDNN [26 (15.5–35) vs 36 (30–40.25) ms, P = 0.002], RMSSD [25.9 (11.95–40.45) vs 36.65 (27.05–44.13) ms, P = 0.002], and pNN50 [3.5 (0.23–21.83) vs 16.4 (4.45–27.63) %, P = 0.002] were less in T2DM. Similarly, in frequency domain, low frequency (LF) power [81 (32–148.75) vs 126 (85.25–237.75) ms², P = 0.007], high frequency (HF) power [81 (16.75–187.75) vs 182.5 (121.50–281.75) ms², P = 0.001] and HF nu [54.5 (33.2–63.83) vs 59.7 (50–75.05), P = 0.03] were significantly less in T2DM. Whereas, LF nu [45.25 (35.28–63.93) vs 44.65 (33.7–65.35)] and LF/HF ratio [0.78 (0.54–1.13) vs 0.7 (0.4–1)] were comparable between the groups. In Poincare plot, SD1 [18.5 (8.73–28.98) vs 26.2 (19.33–31.65) ms, P = 0.003] and SD2 [37 (26.13–51.18) vs 48.6 (39.63–56.15) ms, P = 0.016] as well as the ratio of SD1/SD2 [0.18 (0.14–0.21) vs 0.29 (0.25–0.33) P = 0.001] were less in T2DM. However, VPT was comparable between the groups. The patients with T2DM had reduced parasympathetic activity whereas sympathetic activity and vibration (somatic) sensation were similar. It indicates that cardiac parasympathetic activity in T2DM is affected before sympathetic and somatic activity.