In a prospective study, we assessed the effect of CPAP therapy on the insulin sensitivity and CV risk factors such as blood pressure (BP), glycaemia status, and lipid profile in patients with obstructive sleep apnoea (OSA).
Only patients with confirmed presence of cardinal features and diagnostic apnoea/hypopnoea index (AHI) for OSA were enrolled in the study. All patients were studied before the initiation of CPAP therapy. Following an initial screening visit before CPAP treatment, patients were then studied at 6 and 12 weeks following the initiation of CPAP.
We studied 41 patients with confirmed OSA, aged 56 ± 13 (mean ± SD) years, 33 male and 8 female, who had their weight, BP and fasting blood samples checked in a screening visit and two study visits, at least 6 weeks apart. The fasting blood samples were used to assess fasting plasma glucose, HbA1c, fasting insulin, lipid profile, and CRP.
Following CPAP treatment baseline systolic BP had significantly improved compared to BP following CPAP therapy (135 ± 17 vs 123 ± 12 mm Hg, p=0.001) and so did diastolic BP (83 ± 9 vs 77 ± 9 mm Hg, p=0.01). There were also improvement in fasting plasma glucose (5.6 ± 1.7 vs 4.9 ± 2.0 mmol/l, p>0.05) and HbA1c (5.8 ± 1.3 vs 5.4 ± 1.7%, p>0.05), but that was not statistically significant. There had been non-significant improvement of fasting insulin level (17.9 ± 25 vs 12.7 ± 15.5 pmol/l, p>0.05), but no improvement on insulin sensitivity. Lipid profile had also improved, as total cholesterol was decreased (5.2 ± 2.0 vs 4.8 ± 1.9 mmol/l, p>0.05), and so did triglycerides (2.7 ± 4.4 vs 2.0 ± 2.0 mmol/l, p>0.05), but these changes were not statistically significant. CRP had also improved but that was not statistically significant (4.5 ± 10 vs 2.4 ± 2.0 mg/l, p>0.05).
In conclusion, this study demonstrates that CPAP therapy in patients with OSA can result in significant improvement in systolic and diastolic BP, as well as non-significant improvement in lipid profile and glycaemia status.