The relationship between insulin resistance assessed by HOMA-IR and serum osteoprotegerin levels in obesity.
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.
Ugur-Altun
Betul
B
Trakya University, Medical School, Department of Endocrinology and Metabolism, Edirne, Turkey. altun@medscape.com
Altun
Armagan
A
Gerenli
Murat
M
Tugrul
Armagan
A
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*
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