title: Effect of mild hyperglycemia on autonomic function in obstructive sleep apnea.
abstract: BACKGROUND
  Obstructive sleep apnea (OSA) has been hypothesized to cause a hypersympathetic state, which may be the mechanism for the increased incidence of cardiovascular disease in OSA. However, there is a high prevalence of hyperglycemia in OSA patients, which may also contribute to autonomic dysfunction.
  
  
  METHODS
  Thirty-five patients with OSA and 11 controls with average body mass index (BMI) of 32.0 ± 4.6 underwent polysomnography, glucose tolerance testing, autonomic function tests, lying and standing catecholamines, overnight urine collection, and baseline ECG and continuous blood pressure measurements for spectral analysis. A linear regression model adjusting for age and BMI was used to analyze spectral data, other outcome measures were analyzed with Kruskal-Wallis test.
  
  
  RESULTS
  Twenty-three OSA patients and two control patients had hyperglycemia (based on 2001 American Diabetes Association criteria). Apnea-hypopnea index (AHI) correlated with total power and low frequency (LF) power (r = 0.138, 0.177, p = 0.031; and r = 0.013) but not with the LF/high frequency (HF) ratio (p = 0.589). Glucose negatively correlated with LF systolic power (r = -0.171, p = 0.038) but not AHI (p = 0.586) and was marginally associated with pnn50, total power, LF, and HF power (p ranged from 0.07 to 0.08).
  
  
  CONCLUSIONS
  These data suggest that patients with OSA and mild hyperglycemia have a trend towards lower heart rate variability and sympathetic tone. Hyperglycemia is an important confounder and should be evaluated in studies of OSA and autonomic function.
authors.affiliation: Division of Neuromuscular Disorders, Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA. amanda.peltier@vanderbilt.edu
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Peltier
authors.forename: Kanika
authors.initials: K
authors.lastname: Bagai
authors.forename: Kay
authors.initials: K
authors.lastname: Artibee
authors.forename: André
authors.initials: A
authors.lastname: Diedrich
authors.forename: Emily
authors.initials: E
authors.lastname: Garland
authors.forename: Thomas
authors.initials: T
authors.lastname: Elasy
authors.forename: Yaping
authors.initials: Y
authors.lastname: Shi
authors.forename: Lily
authors.initials: L
authors.lastname: Wang
authors.forename: Eva L
authors.initials: EL
authors.lastname: Feldman
authors.forename: David
authors.initials: D
authors.lastname: Robertson
authors.forename: Beth A
authors.initials: BA
authors.lastname: Malow
mesh_terms: D000328:Adult; D000368:Aged; D001341:Autonomic Nervous System / Q000503:physiopathology*; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002395:Catecholamines / Q000097:blood; D045422:Continuous Positive Airway Pressure; D003430:Cross-Sectional Studies; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D006943:Hyperglycemia / Q000150:complications*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D002395:Catecholamines; D006454:Hemoglobins; D007328:Insulin; D010100:Oxygen