Obstructive sleep apnea and diabetic nephropathy: a cohort study.
OBJECTIVE
Diabetic 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.


METHODS
This 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 m2. 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.


RESULTS
A 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.


CONCLUSIONS
OSA 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.
Corresponding author: Abd A. Tahrani, a.a.tahrani@bham.ac.uk.
Abd A
AA
Tahrani
Asad
A
Ali
Neil T
NT
Raymond
Safia
S
Begum
Kiran
K
Dubb
Quratul-Ain
QA
Altaf
Milan K
MK
Piya
Anthony H
AH
Barnett
Martin J
MJ
Stevens
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000097:blood / Q000453:epidemiology / Q000209:etiology; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000196:embryology*; D003928:Diabetic Nephropathies / Q000453:epidemiology*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000150:complications; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*
D015415:Biomarkers