title: A simple deep breathing test reveals altered cerebral autoregulation in type 2 diabetic patients.
abstract: OBJECTIVE
  Patients with diabetes mellitus have an increased risk of stroke and other cerebrovascular complications. The purpose of this study was to evaluate the autoregulation of cerebral blood flow in diabetic patients using a simple method that could easily be applied to the clinical routine screening of diabetic patients.
  
  
  METHODS
  We studied ten patients with type 2 diabetes mellitus and 11 healthy volunteer control participants. Continuous and non-invasive measurements of blood pressure and cerebral blood flow velocity were performed during deep breathing at 0.1 Hz (six breaths per minute). Cerebral autoregulation was assessed from the phase shift angle between breathing-induced 0.1 Hz oscillations in mean blood pressure and cerebral blood flow velocity.
  
  
  RESULTS
  The controls and patients all showed positive phase shift angles between breathing-induced 0.1 Hz blood pressure and cerebral blood flow velocity oscillations. However, the phase shift angle was significantly reduced (p < 0.05) in the patients (48 +/- 9 degrees ) compared with the controls (80 +/- 12 degrees ). The gain between 0.1 Hz oscillations in blood pressure and cerebral blood flow velocity did not differ significantly between the patients and controls.
  
  
  CONCLUSIONS
  The reduced phase shift angle between oscillations in mean blood pressure and cerebral blood flow velocity during deep breathing suggests altered cerebral autoregulation in patients with diabetes and might contribute to an increased risk of cerebrovascular disorders.
authors.affiliation: Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany. clivemartin.brown@unifr.ch
authors.forename: C M
authors.initials: CM
authors.lastname: Brown
authors.forename: H
authors.initials: H
authors.lastname: Marthol
authors.forename: U
authors.initials: U
authors.lastname: Zikeli
authors.forename: D
authors.initials: D
authors.lastname: Ziegler
authors.forename: M J
authors.initials: MJ
authors.lastname: Hilz
mesh_terms: D001944:Breath Tests; D002560:Cerebrovascular Circulation; D003924:Diabetes Mellitus, Type 2 / Q000503:physiopathology*; D003971:Diastole; D005260:Female; D006339:Heart Rate; D006706:Homeostasis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012143:Respiratory Physiological Phenomena; D013599:Systole