title: Lack of association between impaired glucose tolerance and appetite regulating hormones in patients with obstructive sleep apnea.
abstract: OBJECTIVE
  Understanding the etiologic mechanisms underlying impaired glucose tolerance in obstructive sleep apnea (OSA) would assist development of therapies against this comorbidity. We hypothesized that in patients with OSA impaired glucose tolerance (IGT) would be associated with elevated levels of hormones associated with appetite regulation (leptin, ghrelin, neuropeptide Y [NPY] and peptide tyrosine-tyrosine [PYY]).
  
  
  METHODS
  We studied 68 OSA patients (mean AHI 22 events/h) and 37 age and weight matched healthy controls recruited by advertisement. All participants received a standardized evening meal, attended polysomnography and an oral glucose tolerance test (OGTT) on waking. Hormones were measured in blood taken before sleep (22:30) and at the start of the OGTT.
  
  
  RESULTS
  Impaired glucose tolerance was present in 54% of patients and 32% of controls (p = 0.05). The only differences between groups was that leptin was significantly higher at 22:30 in OSA patients compared to controls (9.6 ng/L vs 7.9 ng/L, p = 0.05). OSA patients had marginally elevated plasma NPY levels at 22:30 (56.6 [52, 67] pmol/L vs 51.1[47.3, 61] pmol/L; p = 0.04). No differences in ghrelin, PYY or NPY were observed between patients with IGT and those without. However OSA patients with IGT had significantly higher value of leptin at both 22:30 (10.9 [7.7, 15.9] ng/mL vs 7.4 [5.6, 12.3] ng/mL, p = 0.02) and 07:00 (11.6 [7.6, 16.2] ng/mL vs 6.9 [5.4, 12.6] ng/mL, p = 0.024) than those without. In multivariate analysis the only major association of leptin was body mass index.
  
  
  CONCLUSIONS
  Clinically significant abnormalities of appetite regulating hormones are not present in OSA. Appetite regulating hormones did not differ in OSA patients with and without impaired glucose tolerance.
authors: NIHR Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London, London, UK.
authors: Ioannis
authors: I
authors: Papaioannou
authors: Michael
authors: M
authors: Patterson
authors: Gillian L
authors: GL
authors: Twigg
authors: Ali
authors: A
authors: Vazir
authors: Mohammad
authors: M
authors: Ghatei
authors: Mary J
authors: MJ
authors: Morrell
authors: Michael I
authors: MI
authors: Polkey
mesh_terms: D001786:Blood Glucose; D004151:Dipeptides / Q000097:blood; D054439:Ghrelin / Q000097:blood*; D018149:Glucose Intolerance / Q000097:blood* / Q000150:complications*; D005951:Glucose Tolerance Test; D006801:Humans; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D009478:Neuropeptide Y / Q000097:blood; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications*
chemical_list: D001786:Blood Glucose; D004151:Dipeptides; D054439:Ghrelin; D020738:Leptin; D009478:Neuropeptide Y; C042696:tyrosyltyrosine