Association of osteopontin and tumor necrosis factor-α levels with insulin resistance in obese patients with obstructive sleep apnea syndrome.

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.