Title Blood pressure regulation in diabetics with and without peripheral neuropathy Authors

Cardiac and vascular dysfunctions resulting from autonomic neuropathy (AN) are complications of diabetes, often undiagnosed. Our objectives were to: 1) determine sympathetic and parasympathetic components of compromised blood pressure regulation in patients with peripheral neuropathy, and 2) rank noninvasive indexes for their sensitivity in diagnosing AN. We continuously measured ECG, arterial blood pressure (BP) and respiration during supine rest and 70o head-up tilt in 12 able-bodied subjects (AB), 7 diabetics without, 7 diabetics with possible, and 8 diabetics with definite, sensory and/or motor neuropathy (D2). During the first 3 min of tilt, systolic BP (SBP) of D2 decreased (-10.9 ± 4.5 (SEM) mmHg), but increased in AB (+4.8 ± 5.4 mmHg). Compared to AB, D2 had smaller low frequency (0.04-0.15 Hz) spectral power of diastolic BP, lower baroreflex effectiveness index (BEI) and more SBP ramps. Except for low frequency power of SBP, D2 had greater SBP and smaller RR Interval harmonic and nonharmonic components at rest across the 0.003 0.45 Hz region. In addition, our results support previous findings of smaller HF RR interval power, smaller numbers of baroreflex sequences and lower baroreflex sensitivity in D2. We conclude that diabetic peripheral neuropathy is accompanied by diminished parasympathetic and sympathetic control of heart rate and peripheral vasomotion and diminished baroreflex regulation. A novel finding of this study lies in the sensitivity of BEI to detect autonomic neuropathy, presumably due to its combination of parameters that measure reductions in both sympathetic control of vasomotion and parasympathetic control of heart rate.