Association of Diabetic Microvascular Complications and Parameters of Obstructive Sleep Apnea in Patients with Type 2 Diabetes

Background: Obstructive sleep apnea (OSA) is prevalent in patients with type 2 diabetes, but the influence of OSA on diabetes complications is not clear. We aimed to investigate the association of OSA with chronic diabetes complications in Chinese patients with type 2 diabetes. Subjects and Methods: In total, 880 hospitalized patients were enrolled in a multicenter, cross-sectional study that involved 12 hospitals from six cities in the People's Republic of China. Overnight sleep monitoring with a portable monitor was used to record respiratory parameters, including the apnea–hypopnea index (AHI), the oxygen desaturation index (ODI), the oxygen saturation (SPO2), and the cumulative time of SPO2 below 90% or 85% (CT90% and CT85%, respectively). Chronic diabetes complications were recorded from medical charts. Results: CT90% was independently associated with diabetic nephropathy (DN) after adjusting for age, sex, diabetes duration, glycosylated hemoglobin, body mass index, hypertension, and the use of angiotensin converting enzyme inhibitor/angiotensin receptor blocker drugs within 1 week. The associated parameters increased from two (the average SPO2 and CT90%) to three (ODI, the lowest SPO2, and CT85%) when the severity of DN increased from microalbuminuria to renal insufficiency. The estimated glomerular filtration rate was independently correlated with ODI (β = −0.172, P = 0.029) and the lowest SPO2 (β = 0.354, P = 0.004) after adjustments. The lowest SPO2 was associated with proliferative diabetic retinopathy by univariate logistic regression but was not significant in multivariate regression after adjustment. Conclusions: Parameters of nocturnal hypoxemia are associated with DN and renal function of patients with type 2 diabetes. The parameters of hypoxemia may more sensitively reflect the association of OSA and diabetic microvascular complications than AHI.