Prevalence of obstructive sleep apnea in Type 2 diabetes mellitus

A study was conducted to assess the prevalence of OSA in a small population of Type 2 Diabetes mellitus and further observe any correlations.

(1) To study the prevalence of OSA in T2DM; (2) To study the role of Diabetes mellitus as a risk factor for OSA; (3) The role of OSA in glycemic control in patients with Diabetes mellitus. Material & Methods: Three hundred and twenty five patients of T2DM attending the Out Patients Department (Medicine & Diabetes Clinic) of Safdarjang Hospital & Vardhman Mahavir Medical College were randomly selected for the study. They were asked to fill the Berlin's Questionnaire for sleep apnea. The patients were aged 35–75 years. Based on their response to this questionnaire, the patients were classified as either “high risk group” or “low risk group” for OSA. All such patients underwent complete physical examination and overnight polysomnography. Level -1 Polysomnography was conducted in the sleep laboratory of the institution.

Amongst the 325 patients recruited for the study, 85 patients were identified as falling in the risk group on the basis of response to Berlin Questionnaire. After PSG, 79 patients were found to have significant sleep disordered breathing. Amongst the 325 patients of T2DM who were screened with Berlin Questionnaire, 16.3%belonged to the high risk group and 9.9% to the low risk group. The prevalence of OSA in type 2 DM was found to be 24.3% (Males 28%, females 19.9%). Majority of patient of the high-risk group had severe OSA and majority of the low-risk group patient had mild OSA. There was significant difference (p=0.007) in body mass index between patients of T2DM with OSA (29.012 + 5.971). There was significant difference in arousal index (AI), desaturation index (DI), minimum oxygen saturation (O₂ sat_min) and respiratory disturbance index (RDI) between the high-risk & low risk groups of patients of T2DM with OSA. A positive and significant correlation was found between BMI and various sleep parameters like RDI, DI and O₂sat_min. There was a positive and significant correlation between HbA₁c and various sleep parameters like RDI, DI and O₂ sat_min.

This study found a higher prevalence of OSA in patients of T2DM as compared to the general population. There may be an aspect of central obesity in T2DM which contributes to OSA as reflected in BMI and neck circumference, which was also found to be higher in the diabetic population than in general population. An increased level of HbA₁c was found to be associated with increased severity of OSA. HbA1c alone was found to contribute to about 21. 9% variation in RDI.