Instability Of Cerebral Blood Flow In Diabetic Patients With Cardiovascular Autonomic Neuropathy And Orthostatic Hypotension

Abstract

Cardiovascular autonomic neuropathy (CAN) is a risk factor for stroke in people with diabetes mellitus, and orthostatic hypotension (OH) is a feature of CAN. Therefore, the purpose of this study was to evaluate the mean cerebral blood flow velocity (MFV) in response to standing up in patients with diabetes and OH. We studied 27 patients with diabetes mellitus, among whom 8 had CAN and OH (OH+, age: 46.4 ± 13.5 years, diabetes duration: 25.0 ± 11.0 years; mean ± SD), 7 had CAN but without orthostatic hypotension (OH‐, age: 47.3 ± 12.7, diabetes duration: 26.4 ± 12.1 years), 12 had no evidence of CAN (CAN‐, age: 44.1 ± 13.8, diabetes duration: 17.1 ± 10.2 years), and 14 control subjects (age: 42.6 ± 9.1 years). The MFV in the right middle cerebral artery was recorded using transcranial Doppler sonography in the supine position after 15 minutes of rest and immediately after standing up. The change from the supine position to standing resulted in a pronounced drop in mean blood pressure in the OH+ group (−14.0 ± 20.9 mmHg), while there were no significant changes in blood pressure in the other groups. MFV in the supine position was not different between the diabetic (either with or without CAN or OH) and control groups. However, the relative percentage changes in MFV immediately after standing up were −23.3 ± 17.2% in OH+, +0.6 ± 14.6% in OH‐, −2.3 ± 15.1% in CAN‐, and −10.5 ± 11.1% in the control group (p < 0.05 for OH+ vs. the other groups). Patients with diabetes mellitus complicated by CAN and OH may show instability in cerebral blood flow regulation on standing. Whether this finding is associated with a higher susceptibility to stroke in these patients remains to be established in prospective studies.