title: IGF-1 Levels are Inversely Associated With Metabolic Syndrome in Obstructive Sleep Apnea.
abstract: OBJECTIVE
  This study examined insulin-like growth factor-1 (IGF-1) production and its association with the metabolic syndrome (MS) in men with obstructive sleep apnea (OSA).
  
  
  METHODS
  In total, 47 overweight and obese men who had been referred for suspected OSA underwent polysomnography and were classified based on the apnea-hypopnea index (AHI) into three groups: no OSA, < 5 events/h (n = 11); mild OSA, ≥ 5 to < 15 events/h (n = 8); and moderate-severe OSA, ≥ 15 events/h (n = 28). The assessment of the somatotropic axis function included IGF-1 measurement. MS was diagnosed according to the National Cholesterol Education Program guidelines.
  
  
  RESULTS
  IGF-1 level in the moderate-severe OSA group was lower than in the no-OSA group (156.8 ± 54.3 μg/L versus 225.5 ± 80.5 μg/L; p = 0.013). IGF-1 level was negatively correlated with body mass index, waist circumference (WC), AHI, and sleep duration with oxygen (O2) saturation < 90% and positively correlated with the average and minimum O2 saturation (p = 0.027). In a multivariable linear regression, considering WC and minimum O2 saturation as independent variables, only the minimum O2 saturation was a predictor of low IGF-1 levels. The proportions of patients with MS were different between the three groups (18.2% in no OSA; 25% in mild OSA, and 57.1% in moderate-severe OSA; p = 0.047). Furthermore, in the lowest tertile of IGF-1 value, 66.7% of patients were affected by MS (p = 0.049). Hemoglobin (Hb)A1c correlated negatively with the minimum O2 saturation and IGF-1 levels. However, in multivariable linear regression only IGF-1 levels were a predictor of HbA1c levels.
  
  
  CONCLUSIONS
  The occurrence of OSA is associated with a reduction in IGF-1 levels. IGF-1 alterations in OSA also seem to be associated with a higher prevalence of MS.
authors.affiliation: Department of Endocrinology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Suelem
authors.initials: S
authors.lastname: Izumi
authors.affiliation: Department of Endocrinology, Universidade Federal do Pará, PA, Brazil.
authors.forename: Fernando F
authors.initials: FF
authors.lastname: Ribeiro-Filho
authors.affiliation: Department of Endocrinology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Gláucia
authors.initials: G
authors.lastname: Carneiro
authors.affiliation: Department of Psycobiology, Sleep Disorders Center, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Sônia M
authors.initials: SM
authors.lastname: Togeiro
authors.affiliation: Department of Psycobiology, Sleep Disorders Center, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Sérgio
authors.initials: S
authors.lastname: Tufik
authors.affiliation: Department of Endocrinology, Universidade Federal de São Paulo, SP, Brazil.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Zanella
mesh_terms: D000328:Adult; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood* / Q000150:complications*; D008875:Middle Aged; D017286:Polysomnography; D012307:Risk Factors; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000150:complications*
chemical_list: D007334:Insulin-Like Growth Factor I
keywords: GH/IGF-1 axis; IGF-1; insulin-like growth factor-1; metabolic syndrome; obstructive sleep apnea