Metabolic Abnormalities in Obstructive Sleep Apnea Patients

Abstract

Introduction: OSA is a well-recognized risk factor of cardiovascular disorders and is related to metabolic syndrome. The aim of this study was to evaluate the effect of BMI and AHI/RDI on metabolic disturbances in patients suspected of OSA. Material and methods: Ninety-nine patients referred with suspected OSA underwent standard polysomnography or limited sleep study. AHI/RDI ≥ 10/h was considered relevant for OSA diagnosis. Subjects with AHI/RDI < 10 were considered as controls. We assessed apnea-hypopnea index or respiratory disturbances index (AHI/RDI), Epworth sleepiness scale (ESS), body mass index (BMI), C-reactive protein (CRP, mg/L), glycosylated haemoglobin (HbA1c, %), fasting serum total cholesterol, HDL-, LDL-cholesterol, triglycerides (TG), glucose (G), insulin (INS, IU/mL) and HOMA index. Results: Data are presented as mean ± SD or median (interquartile range) for parametric and nonparametric data respectively. Twenty-two patients were included as controls (age 51.8 ± 10 vs. 55 ± 11 in OSA; p = NS). AHI/RDI in the OSA group was 23 (16–31.3) and 7 (3.8–8.1) in controls (p < 0.001). BMI in OSA 32.2 ± 5.8 vs. 30.4 ± 4.6 in controls (p = NS). Patients with OSA had higher TG (160 ± 75.9 vs. 130.2 ± 51.9 mg/dL, p = 0.046), G (5.04 ± 0.6 vs. 4.47 ± 0.6, p = 0.0037), HOMA (2.31 ± 1.5 vs. 1.85 ± 1.7, p = 0.046). G correlated best with AHI/RDI (p < 0.001, r = 0.41). Significant differences were observed in OSA patients between obese (51 pts, BMI 35.2 ± 4.8) and non-obese (26 pts, BMI 26.61 ± 1.9) pts in: HDL-cholesterol (50.8 ± 13.2 vs. 60.9 ± 18.4 mg/dL; p = 0.02), TG (178.7 ± 69.9 vs. 124 ± 75.3 mg/dL, p < 0.001), G (5.15 ± 0.7 vs. 4.8 ± 0.5 mmol/L, p = 0.01), INS (11.7 ± 5.9 vs. 6.57 ± 4.7, p < 0.001), HOMA (2.7 ± 1.4 vs. 1.4 ± 1.2, p < 0.001), HbA1c (5.89 ± 0.9 vs. 5.4 ± 0.8, p = 0.03), CRP (2.2 ± 2.9 vs. 1.09 ± 1.2, p = 0.01). Conclusions: Our findings support the results of previous studies showing the influence of OSA alone on metabolic disturbances. However, BMI has major impact on metabolic variables.