Prevalence and associations of obstructive sleep apnea in South Asians and White Europeans with type 2 diabetes: A cross-sectional study

Study Objectives: To assess and compare obstructive sleep apnea (OSA) prevalence in South Asians and White Europeans with type 2 diabetes mellitus (T2DM). Secondary aims included exploring possible causes for observed ethnic differences. Methods: A cross-sectional study of patients with T2DM recruited from secondary care diabetes clinics. OSA was defined as an apnea-hypopnea index (AHI) > 5 events/h using home-based, multi-channel respiratory monitoring. Results: Two hundred thirty-four patients (105 South Asian and 129 White Europeans) were studied. The prevalence of mild, moderate, and severe OSA in South Asians was 36.2% (n = 38/105), 9.5% (n = 10/105), and 5.7% (n = 6/105) respectively. After adjustment, OSA was associated with a higher body mass index in South Asians. OSA was significantly less common in South Asians compared to White Europeans (51.4% [54/105] versus 75.2% [97/129], P <.001). OSA was also less severe in South Asians compared to White Europeans (median [interquartile range]: AHI 5.1 [1.4-11.5] versus 8.5 [5.0-20.7] events/h, P <.001; time spent with oxygen saturations < 90% 0.5 [0.0-2.9]% versus 4.0 [0.7-14.4]%, P <.001). Logistic regression showed that only obesity measures explained the ethnic differences in OSA. Conclusions: South Asians with T2DM are at considerable risk of OSA. OSA in South Asians was associated with obesity. However, OSA prevalence was lower in South Asians than in White Europeans. Obesity measures accounted for the observed ethnic differences. Examining factors contributing to ethnic differences will be important to inform screening and treatment strategies.