Abstract
Background: The effects of nasal continuous positive airway pressure (nCPAP) for obstructive sleep apnoea (OSA) on insulin resistance (IR) are not clear and have found conflicting results.
Aims and objectives: To evaluate IR in non diabetic patients with moderate to severe OSA and the effect of treatment with nCPAP on IR in these patients.
Method: 30 consecutively newly diagnosed patients with moderate to severe OSA were enrolled in the study. Samples of peripheral venous blood for measurement of glucose and insulin were collected after overnight fasting and IR was calculated by HOMA (Homeostasis model assessment) method. Patients were treated with nCPAP for 1month and HOMA IR was again measured.
Results: 30 OSA subjects,with a mean apnoea-hypopnoea index (AHI) of 80.46 [57.24] were included in the study. The HOMA IR (5.78) was significantly higher compared to normal south indian population. There was no positive correlation of HOMA IR with AHI. This may be due to the small sample size and IR attributable to OSA may be small and constant and not related to the severity. The HOMA IR was measured 1 month after use of CPAP. The HOMA IR significantly improved from 5.78 to 4.82 (p=0.024) after 1 month of treatment with nCPAP in OSA patients. There was also significant improvement in insulin levels from 21.75 to 19.39 (p=0.009).
Conclusion: OSA is associated with an increase in IR which may be one of the reasons that OSA is a risk factor for coronary artery disease (CAD). Treatment with CPAP rapidly improves the insulin sensitivity in patients with OSA and thus may contributes to a reduction of cardiovascular risk in patients with moderate to severe OSA.
- © 2011 ERS