Cardiovascular autonomic neuropathy in type 2 diabetes mellitus patients with peripheral artery disease

OBJECTIVE: To evaluate possible associations between cardiovascular autonomic dysfunction and peripheral artery disease (PAD) in patients with type 2 diabetes mellitus. RESEARCH DESIGN AND METHODS: In this cross-sectional study, 67 patients with type 2 diabetes were included. PAD was identified by Doppler ultrasonography: systolic ankle-brachial pressure index <0.9. Cardiovascular autonomic function, besides five conventional cardiovascular autonomic function tests, was assessed by heart rate variability (HRV; 24-h ambulatory ECG recording) in time and frequency domains (spectral analyses) and three dimensional return maps. Power spectral analyses (PSA) were quantified in low frequency (LF), high frequency (HF), and very low frequency. RESULTS: Patients with PAD (n = 30) had longer diabetes duration, higher systolic blood pressure (BP), waist-to-hip ratio, HbA1C test, and urinary albumin excretion (UAE) than patients without PAD. Most HRV indices in time domain were lower in patients with than without PAD. These patients also had lower PSA indices (LF=0.19±0.07 vs. 0.29±0.11 n.u.; LF/HF ratio=1.98±0.9 vs. 3.35±1.83; P<0.001) and indices of sympathetic (three-dimensional return map: P(1)-night 61.7±9.4 vs. 66.8±9.7; P=0.04) and vagal (24-h P(2) 54.5±15.2 vs. 62.7±2.9; P< 0.02) activities (arbitrary units) than patients without PAD. Multivariate logistic regression analyses, adjusted for systolic BP, DM duration, HbA1C test, and UAE, confirmed the associations between impaired autonomic modulation and PAD, except for P(1) index. CONCLUSION: In conclusion, patients with type 2 diabetes with PAD had lower HRV indices than patients without PAD, reflecting a dysfunction of cardiovascular autonomic modulation.