title: The relationship between insulin resistance assessed by HOMA-IR and serum osteoprotegerin levels in obesity.
abstract: OBJECTIVE
  We investigated the relationship between insulin resistance and serum osteoprotegerin (OPG) levels in healthy obese subjects and healthy lean controls.
  
  
  METHODS
  Fifty obese subjects (age: 31+/-8 years) and 24 lean controls (age: 30+/-7 years) were included in the study. We used the homeostasis model assessment for insulin resistance (HOMA-IR) index as the index of insulin resistance. OPG levels were measured with the commercial ELISA kit. Obese subjects were studied in three groups: Group I (n = 25) HOMA-IR index < 2.24, Group II (n = 13) index 2.24-3.59, Group III (n = 12) index > 3.59. Group IV (n = 24) was the lean controls with HOMA-IR index < 2.24.
  
  
  RESULTS
  Obese subjects with increased insulin resistance (Group III) had lower OPG values than other groups (11.88+/-7.43 pg/ml, 16.39+/-6.39 pg/ml, 17.37+/-9.61 pg/ml, and 18.1+/-6.65 pg/ml, respectively; Group I versus Group III p = 0.036; Group III versus Group IV p = 0.012). We also found significant inverse correlations between OPGc (corrected for BMI) and fasting glucose (r = -0.325, p = 0.005), fasting insulin (r = -0.404, p = 0.0001) as well as HOMA-IR (r = -0.428, p = 0.0001). Increased fibrinogen level was found in Group III than Group IV (9.32+/-1.97 micromol/l versus 7.47+/-1.65 micromol/l, respectively; p = 0.005). In conclusion, insulin resistance in obesity is associated with decreased serum OPG levels and increased fibrinogen levels. The relationship between serum OPG levels and HOMA-IR may provide an insight into vascular endothelial dysfunction in obesity.
authors.affiliation: Trakya University, Medical School, Department of Endocrinology and Metabolism, Edirne, Turkey. altun@medscape.com
authors.forename: Betul
authors.initials: B
authors.lastname: Ugur-Altun
authors.forename: Armagan
authors.initials: A
authors.lastname: Altun
authors.forename: Murat
authors.initials: M
authors.lastname: Gerenli
authors.forename: Armagan
authors.initials: A
authors.lastname: Tugrul
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005215:Fasting / Q000097:blood; D005260:Female; D005340:Fibrinogen / Q000378:metabolism; D006023:Glycoproteins / Q000097:blood*; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008297:Male; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear / Q000097:blood*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*
chemical_list: D001786:Blood Glucose; D006023:Glycoproteins; D007328:Insulin; D053244:Osteoprotegerin; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D005340:Fibrinogen