Effects of Cardiac Autonomic Neuropathy on Blood Pressure, Aortic Stiffness, and Central Pressure Loading in Patients with Type 2 Diabetes

Abstract

Background: Obstructive sleep apnea (OSA) is characterised by repetitive hypoxia/reoxygenation, due to reoccurring apneas and hypopneas, and is associatedwith endothelial dysfunction and reduced circulating levels of endothelial progenitor cells (EPCs). The potential to improve endothelial function and regenerative capacity in people with OSA by preventing hypoxic episodes with Continuous Positive Airway Pressure (CPAP) was investigated in the first sham-controlled CPAP study. Methods: Men with moderate-to-severe OSA (age= 49± 12 y, apnea hypopnea index (AHI) = 37.6± 16.4 events/h, body mass index= 31.5± 5.7 kg/m2), who were CPAP naive, without diabetes mellitus, were randomised in a 12-week double-blind sham-controlled parallel group study to receive either active (n= 25) or sham (n= 21) CPAP. Cir[SBP]). Methods:PtswithT2DM(n= 188, 59± 9 y, 53%men), but no coronary artery disease, were screened for CAN using current criteria of ≥2 abnormal findings from a clinical test battery comprising four cardiac reflex tests and three heart rate (HR) variability spectral parameters. In addition to resting brachial BP and aortic (carotid-femoral) PWV, we recorded radial tonometry for central BP, augmented pressure and AIx. Results: CAN was identified in 30 (16%)pts, who were older (p= 0.056), had higher HbA1c (p= 0.002), higher triglycerides (p= 0.067) and were more likely to be female (p= 0.007) and taking insulin (p= 0.013) and calcium channel blockers (p= 0.094). Unadjusted brachial and central SBP, central augmented pressure, AIx and aortic PWV were all raised in CAN pts (Table). However, after correction for clinical differences and other confounders (including antihypertensive medications), only aortic PWV remained elevated in the presence of CAN.