Objective: The aims of this study were to compare the tumor necrosis factor (TNF)-α and osteopontin levels, to identify the relationship between insulin resistance (IR) and osteopontin levels in obese patients with and without obstructive sleep apnea syndrome (OSAS).
Method: The study population included 62 obese patients (35 males, 27 females) with OSAS and was compared with 26 obese patients (16 males, 10 females) without OSAS as a control group. Polysomnographic evaluation, spirometric tests and arterial blood gas sampling were performed on the obese patients with OSAS. Plasma levels of TNF-α and osteopontin were measured by enzyme-linked immunosorbent assays during the process. IR was estimated using the homeostasis model assessment (HOMA).
Results: Mean plasma levels of fasting glucose, insulin, HOMA, liver function test, hematocrit, leukocyte, TSH, free T4, fibrinogen, TNF-α, and osteopontin were similar in the 2 groups. In patients with OSAS, mean osteopontin levels were positively correlated with mean fasting insulin levels (r=0.306, p=0.01), HOMA (r=0.299, p=0.01), apnea-hypopnea index (r=0.377, p=0.03) and Epworth Sleepiness Scale (r=0.299, p=0.01). However, mean TNF-α levels were negatively correlated with Epworth Sleepiness Scale (r=-0.298, p=0.01) in the patients with OSAS.
Conclusions: It was observed that TNF-α and osteopontin levels showed no difference between obese patients with and without OSAS. However, osteopontin levels increased with fasting insulin, IR, OSAS severity, and daytime sleepiness.