title: Cardiac autonomic balance and QT dispersion during head-up tilt testing in diabetics with and without sensory neuropathy.
abstract: BACKGROUND
  Cardiovascular autonomic dysfunction is associated with higher mortality in diabetics. However, detection methods of early cardiac diabetic dysautonomia, and its correlation with severity of sensory neuropathy, have not been described.
  
  
  METHODS
  We analyzed the heart rate variability (HRV) by spectral analysis and QT dispersion in 23 diabetics with and without sensory neuropathy, and in 5 age-matched controls, in the supine position and during head-up tilt testing (HUT). Diabetics were divided into 3 groups according to the degree of sensory neuropathy.
  
  
  RESULTS
  In the spectral analysis of HRV, the high frequency components in the supine position decreased as a function of severity of the neuropathy. High frequency in diabetics was significantly decreased in the supine position, even in absence of sensory neuropathy. The low/high frequency ratio (L/H) in the supine position was similar among controls and the 3 patient groups. L/H in diabetics with moderate or severe neuropathy did not increase from the supine to the upright position. Baseline QT dispersion increased proportionally to the severity of sensory neuropathy and, in patients without apparent sensory neuropathy, QT dispersion increased significantly during HUT.
  
  
  CONCLUSIONS
  The spectral analysis of HRV and measurements of QT dispersion, before and during HUT, were reliable detection methods of early abnormalities in autonomic balance and may predict a risk of sudden cardiac death in diabetics.
authors.affiliation: The First Department of Internal Medicine, University of Occupational and Environmental Health, Yahatanishi, Kitakyushu, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Tanikawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Abe
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Yasuhide
authors.initials: Y
authors.lastname: Nakashima
mesh_terms: D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000503:physiopathology; D016022:Case-Control Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology; D003924:Diabetes Mellitus, Type 2 / Q000150:complications* / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016683:Supine Position; D018667:Tilt-Table Test