Vascular Endothelial Function And Insulin Resistance In Patients With Obstructive Sleep Apnea-Hypopnea Syndrome

Objectives: By measuring fasting serum insulin level and endothelium-dependent brachial artery dilation (flow-mediated dilation, FMD),to investigate the impacts of obstructive sleep apnea-hypopnea syndrome (OSAHS) on insulin resistance, artery dilating function and their relationship. To study the pathologic and physiological changes of endocrine as well as cardiovascular system,and their mechanism in the cases of OSAHS.Methods: Twenty patients with moderate or severe OSAHS(AMI>20/h) and twenty non-OSAHS controls were included in this study. The brachial artery baseline diameter(d1) and reactive hyperemia diameter (d2) were measured in all subjects. FMD was defined as the percentage change in diameter between baseline and reactive hyperemia ( (d2-d1)/d1 × 100% ) .Venous blood was sampled in the fasting state and plasma glucose was measured by glucose oxidase method,serum insulin level was measured by radioimmunoassay, insulin resistance was assessed by Homeostasis Model Assessment(HOMA) method. Data were processed by t-test statistically and the relationship among serum insulin resistance , FMD and sleep parameters were analyzed.Results: OSAHS patients had lower FMD compared with non-OSAHS controls(5. 9±1. 46% vs 10 ± 1.96%, p< 0. 05) ;OSAHS patients had higher HOMA-IR compared with non-OSAHS controls (1. 2725 ± 0. 6760 vs 0.4696 ± 0. 3314,p < 0.05).In OSAHS patients, fasting serum insulin levelcorrelated positively with AHI, ODI, BMI (r=0. 6257 , 0.5722, 0.6887, respectively , p<0. 05), negatively with FMD(r=-0. 4909, p<0. 05) ; HOMA-IR correlated positively with AHI,ODI,BMI (r= 0.6066 , 0.5804 , 0. 6215, respectively ;p<0. 05), negatively with FMD ( r=-0. 4448, p< 0. 05) ; FMD correlated negatively with AHI (r=-0.4742,p < 0.05). Other associations were not observed.Conclusions:In the patients with OSAHS,insulin resistance, lower insulin bioactivity and impaired endothelial function was existed. Correlation and interaction between insulin resistance and endothelial dysfunction was confirmed.