Serum Homocysteine Levels , Insulin Resistance And Their Relationship In Patients With Obstructive Sleep Apnea Syndrome(OSAS)

Introduction Obstructive sleep apnea syndrome (OSAS) is a common sleep related-breathing disorder. Recent researches showed that OSAS was an independent risk factor of cerebral infarction, and it was also closely related to several other risk factors of cerebral infarction such as hypertension, diabetes and coronary artery disease, etc. It had been found that Insulin resistance and Hyperhomocysteinemia(HHcy) was present in OSAS patients;And insulin resistance could result in HHcy, and the latter was an independent risk of cerebral infarction. However, if OSAS can lead to HHcy by insulin resistance and sequentially increase the occurrence of cerebral infarction ? No relative study had been reported according to the references. This study, by detection of the levels of insulin resistance, Hcy in patients with OSAS , and by correlative analysis between them, mainly explored the HHcy and insulin resistance related mechanism that OSAS induced cerebral infarction.Materials and Methods The enrollments were the inpatients or outpatients who accepted the portable polysomnography in Cadres Wards of Peking University Shenzhen Hosipital from January to September in 2009. Sleepiness score was measured in all participants with the Epworth Sleepiness Scale. The participants were then divided into the OSAS group(n=22) and the controll group(n=20) according to the results of portable polysomnography. The fastings serum Hcy, glucose, insulin and lipids were detected in the morning after the polysomnography had been completed. The homeostatic model assessment of insulin resistance (HOMA-IR) had been calculated by the formula: HOMA-IR=insulin (μIU/ml)×glucose (mmol /L)/22.5. Then the levels of Hcy, HOMA-IR were compared between two groups, and the mutual relationship between HOMA-IR and apnea hypopnea index (AHI), Hcy and AHI, Hcy and HOMA-IR of participants were analyzed.Results Hcy and HOMA-IR levels in OSAS group were significantly higher than those of the control (18.043±6.967versus11.835±4.156;4.510±2.877versus2.755±1.124 respectively). The HOMA- IR and Hcy were positively correlated with AHI in OSAS patients[(r=0.779,P<0.01),(r=0.845,P<0.01)] , and this kind of correlation still existed after the interference of BMI and year were controlled by partial correlation analysis[(r'=0.525,P'<0.05),(r'=0.725,P'<0.01)]. Hcy was positively correlated with HOMA-IR in OSAS group(r=0.815,P<0.01). The positive correlations of them remained significant after the interference of BMI and year were controlled by partial correlation analysis(r'=0.715,P'<0.01).Conclusion The Hcy and HOMA-IR levels in OSAS group were higher than those in control (p<0.05); and their levels were positively correlated with the severity of OSAS(p<0.01 for both). The Hcy level was positively correlated with HOMA-IR in OSAS patients (p<0.01). OSAS may affect the metabolism of Hcy, and result in hyperhomocysteinemia by causing insulin resistance,and then HHcy causes cerebral infarction.