IGF1 and obstructive sleep apnea syndrome: Moreover, from the serum IGF-1-related studies we discovered that serum IGF-1 concentrations in patients with OSAHS were reduced independent of disease severity or detection method, and that the serum IGF-1 level was more reduced in patients with OSAHS and high AHI scores, indicating that serum IGF-1 concentration is a possible risk factor for OSAHS.