[Assessment of diabetic cardiovascular autonomic neuropathy by heart rate variability and pulse wave velocity]

Neuropathy is a frequent complication in diabetes mellitus. Since the involvement of the autonomic nervous system indicates a poor prognosis, early detection and subsequent management are important. Analysis of heart rate variability (HRV) provides a quantitative measure of sympathovagal modulation activities on the heart and has been proven to be useful for the early assessment of the diabetic autonomic neuropathy. We recently developed a simple method of measuring pulse wave velocity (PWV) to evaluate sympathetic nervous activity in the vascular system. In this paper, we examined 33 diabetic patients with and without peripheral neuropathy (15 and 18 respectively) using these methods. In time domain analysis, the mean heart rate, standard deviation and coefficient of variation of HRVs significantly differed between these two groups, whereas the indices of PWVs did not show a significant difference. In frequency domain analysis of HRV, both low and high frequency components were decreased, and the low frequency component in normalized unit did not increase after standing in patients with peripheral neuropathy. We previously reported that the mean PWV decreased after standing in patients with diabetic neuropathy. This disagreement suggests that beta sympathetic dysfunction precedes alpha sympathetic dysfunction in diabetic neuropathy.