Igf-1 levels are inversely associated with metabolic syndrome in obstructive sleep apnea

Abstract

Study Objectives: This study examined insulin-like growth factor-1 (IGF-1) production and its association with the metabolic syndrome (MS) in men with obstructive sleep apnea (OSA). Methods: In total, 47 overweight and obese men who had been referred for suspected OSA underwent polysomnography and were classified based on the apnea-hypopnea index (AHI) into three groups: no OSA, < 5 events/h (n = 11)

mild OSA, >= 5 to < 15 events/h (n = 8)

and moderate-severe OSA, >= 15 events/h (n = 28). The assessment of the somatotropic axis function included IGF-1 measurement. MS was diagnosed according to the National Cholesterol Education Program guidelines. Results: IGF-1 level in the moderate-severe OSA group was lower than in the no-OSA group (156.8 +/- 54.3 mu g/L versus 225.5 +/- 80.5 mu g/L

p = 0.013). IGF-1 level was negatively correlated with body mass index, waist circumference (WC), AHI, and sleep duration with oxygen (O-2) saturation < 90% and positively correlated with the average and minimum O-2 saturation (p = 0.027). In a multivariable linear regression, considering WC and minimum O-2 saturation as independent variables, only the minimum O-2 saturation was a predictor of low IGF-1 levels. The proportions of patients with MS were different between the three groups (18.2% in no OSA

25% in mild OSA, and 57.1% in moderate-severe OSA

p = 0.047). Furthermore, in the lowest tertile of IGF-1 value, 66.7% of patients were affected by MS (p = 0.049). Hemoglobin (Hb)A1c correlated negatively with the minimum O-2 saturation and IGF-1 levels. However, in multivariable linear regression only IGF-1 levels were a predictor of HbA1c levels. Conclusion: The occurrence of OSA is associated with a reduction in IGF-1 levels. IGF-1 alterations in OSA also seem to be associated with a higher prevalence of MS.