Obstructive Sleep Apnea and Diabetic Nephropathy A cohort study

OBJECTIVEDiabetic nephropathy (DN) is a leading cause of end-stage renal disease (ESRD). Obstructive sleep apnea (OSA) is common in type 2 diabetes and increases oxidative stress. Hence, OSA could promote the development and progression of DN.RESEARCH DESIGN AND METHODSThis was a cohort study in adults with type 2 diabetes. Patients with known OSA or ESRD were excluded. DN was defined as the presence of albuminuria or an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2). DN progression was based on eGFR measurements. OSA was defined as apnea hypopnea index (AHI) 5 events/h. Serum nitrotyrosine abundance (a marker of nitrosative stress) was measured by ELISA.RESULTSA total of 224 patients were included. OSA and DN prevalence was 64.3 and 40.2, respectively. DN prevalence was higher in patients with OSA (OSA(+)) compared with those without OSA (OSA(-)) (49.3% vs. 23.8%, P < 0.001). After adjustment, OSA (odds ratio 2.64 [95% CI 1.13-6.16], P = 0.02) remained independently associated with DN. After an average follow-up of 2.5 (0.7) years, eGFR decline was greater in OSA(+) compared with OSA(-) patients (median -6.8% [interquartile range -16.1 to 2.2] vs. -1.6% [-7.7 to 5.3%], P = 0.002). After adjusting, both baseline OSA (B = -3.8, P = 0.044) and AHI (B = -4.6, P = 0.02) remained independent predictors of study-end eGFR. Baseline serum nitrotyrosine abundance (B = -0.24, P = 0.015) was an independent predictor of study-end eGFR after adjustment.CONCLUSIONSOSA is independently associated with DN in type 2 diabetes. eGFR declined faster in patients with OSA. Nitrosative stress may provide a pathogenetic link between OSA and DN. Interventional studies assessing the impact of OSA treatment on DN are needed.