The Level Of Serum Leptin And Its Correlation With Insulin Resistance In OSAHS Patients

Objective1.To investigate the changes of fasting serum leptin and insulin level in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients. 2. To study the correlation between serum leptin level and insulin resistance in OSAHS patients.3.To assess the role of serum leptin and insulin resistance in the development of OSAHS.MethodsEight -six male patients diagnosed as OSAHS with 7 hour PSG monitoring were enrolled in this study. OSAHS was defined by apnea-hypopnea index (AHI≥5 events/h). According to their apnea-hypopnea index (AHI), these patient s were divided into two groups :43 cases in the mild/ moderate group and 43 in the severe group. Body height and weight, serum leptin, fasting blood glucose (FBG) and fasting serum insulin ( FINS) were measured and their body mass index (BMI) and HOMA-IR index were calculated afterwards. All the subjects underwent an overnight sleep study in the sleep laboratory. Themain sleep parameters were recorded including: AHI, the minimum oxygen saturation and the nocturnal oxygen saturation . On the morning right after the sleep study, venous blood was sampled in the fasting state for the measurement of glucose, leptin and insulin. Fasting plasma glucose (FPG) was measured by glucose oxidase method. The levels of serum leptin and insulin were measured by radioimmunoassay. Insulin resistance was assessed by Homeostasis Model Assessment method. Serum leptin level, FPG, fasting insulin level, HOMA-IR, and BMI were compared respectively between in the severe OSAHS group and in the mild/ moderate OSAHS group .The correlations of serum leptin level, fasting insulin level, HOMA-IR and sleep parameters were analyzed. Then the correlation between serum leptin level and insulin resistance was evaluated in OSAHS patients.Results:1The nocturnal average SpO2 and nocturnal lowest SaO2 were significantly decreased in the severe OSAHS group than those in the mild-moderate group while the BMI , serum leptin level and HOMA index were increased in the former group with statistical significance .2: The serum leptin level index were positively correlated with AHI and negatively correlated with the nocturnal lowest SaO2 respectively with statistical significance. In addition, serum leptin concentration was also negatively correlated with nocturnal average SaO2 level. 3: The HOMA index were positively correlated with AHI and negatively correlated with the nocturnal lowest SaO2 respectively with statistical significance. The HOMA index was also negatively correlated with nocturnal average SaO2 level.4: In the mild/ moderate group and in the severe group. Serum leptin level was positively correlated with fasting insulin level and and fasting serum insulin and HOMA-IR.Conclusion1. Despite controlling for age, fasting serum leptin level was significantly higher in severe OSAHS patients than that in the mild/moderate subjects. And serum leptin level was correlated with sleep parameters representing the severity of OSAHS, such as AHI, the minimum oxygen saturation and the nocturnal oxygen saturation 2. FPG, fasting insulin level and HOMA-IR in severe OSAHS patients were significantly higher than those in the mild/medorate group ; fasting insulin level and HOMA-IR were correlated with sleep parameters representing the severity of OSAHS, such as AHI, the minimum oxygen saturation and the nocturnal oxygen saturation. Based on the above results, we concluded that OSAHS might correlate with insulin resistance independently. 3. The higher level of serum leptin showed positive correlations with fasting insulin level and HOMA-IR, indicating the correlation between serum leptin level and insulin resistance in OSAHS patients. 4. Hyperlipidemia and hyperinsulinemia were usually present in OSAHS patients the same time, which may be an important reason for the concomitances of 2 diabetes and hypertension. Along the progress of sleep-disordered breathing, metabolic syndrome would be inevitably occur and develop irreversibly, which would increase the morbidity and mortality of cardiovascular diseases.