Abstract
OBJECTIVE: To explore the association of serum vitamin-D levels with the severity of obstructive sleep apnea (OSA) in patients with type 2 diabetes mellitus (T2DM). METHODS: A cross-sectional study of 136 patients with T2DM who underwent overnight polysomnography (PSG) tests and serum 25-hydroxyvitamin-D3 (25(OH)D3) level detections was conducted. Multivariable linear regression and logistic regression analyses were performed to determine the associations of serum 25(OH)D3 levels with apnea-hypopnea index (AHI) and obstructive sleep apnea (OSA). RESULTS: The prevalence rates of OSA were 84.4% for male and 65.2% for female patients, respectively (p = 0.011). With increasing severities of OSA categories (none, mild, moderate and severe), patients were more likely to be male and obese, but there was no significant difference in serum 25(OH)D3 level ((mean ± standard deviation) 21.8 ± 8.8, 27.7 ± 14.6, 24.2 ± 9.8 and 26.8 ± 6.2 ng/mL, respectively, p=0.086). Serum 25(OH)D3 level was not significantly correlated with AHI (log-transformed), with the correlation coefficient of 0.133 (p=0.124). With adjustment for potential confounding factors, multivariable linear regression and logistic regression analyses showed that serum 25(OH)D3 level was not significantly associated with either AHI (log-transformed) or the risk of OSA, with the standardized regression coefficient (95% confidence interval (CI)) of 0.098 (-0.004-0.014, p=0.252) and the adjusted odds ratio (95% CI) of 1.055 (0.991-1.124, p=0.095), respectively. CONCLUSION: Serum 25(OH)D3 level was not significantly associated with either AHI or the risk of OSA in patients with T2DM.