IGFBP4 and obstructive sleep apnea syndrome: Multiple stepwise regression analysis (Table 3) in OSA population showed that AHI scores (β = 0.575, p = .001), HbA1c% (β = 0.390, p = .007), and O2 saturation% (β = −0.417, p = .021) were significant predictors of IGFBP4 (F1,40 = 9.417, p = .006, and r2 = 22%).