title: The impact of hypoxemia on nephropathy in extremely obese patients with type 2 diabetes mellitus.
abstract: OBJECTIVE
  Diabetes mellitus (DM) is associated with obstructive sleep apnea (OSA) and nephropathy. The hypoxemia associated with OSA may exacerbate renal deterioration in DM nephropathy. We examined the role of hypoxemia in the development of DM nephropathy in severely obese patients.
  
  
  METHODS
  This cross-sectional study examined anonymized data from 90 DM patients with extreme obesity attending a weight management service. All patients underwent a routine overnight sleep study. Respiratory parameters measured included apnea-hypopnea index (AHI), mean and minimum oxygen (O2) saturations, and time spent under 90% O2 saturation (%TST < 90%). Chronic kidney disease (CKD+) was defined as estimated glomerular filtration rate (eGFR) ≤ 60 mL/min/1.73 m(2).
  
  
  RESULTS
  Twenty (22%) patients were CKD+. These patients were 7 years older (mean age ± SD 57 ± 11 years, p = 0.003) and had greater adiposity (mean body mass index [BMI] ± SD 50.6 ± 8.7 kg/m(2), p = 0.012). No significant differences were found for median AHI and minimum O2 saturation. %TST < 90% was 4 times greater in CKD+ group (p = 0.046). Multivariate regression analysis showed that AHI (β = -0.17, 95% CI: -0.316 to -0.024) and %TST < 90% (β = -0.215, 95% CI: -0.406 to -0.023) were negatively correlated with eGFR after adjustment for age, gender, BMI, comorbidities, insulin treatment, and drugs affecting the renin-angiotensin system. No associations were found between mean and minimum O2 saturations, and eGFR.
  
  
  CONCLUSIONS
  Apnea and hypopnea events as well as duration of nocturnal hypoxemia were inversely associated with renal function after adjusting for potential confounders. Given the significant burden of renal disease in diabetes, greater vigilance is required in identifying OSA in DM patients with extreme obesity.
authors.affiliation: School of Health and Population Sciences and Birmingham and Black Country NIHR CLAHRC, University of Birmingham, UK ; Specialist Weight Management Services, Heart of England NHS Foundation Trust, Birmingham UK.
authors.forename: Wen Bun
authors.initials: WB
authors.lastname: Leong
authors.affiliation: Academic Department of Sleep and Ventilation, Heart of England NHS Foundation Trust, Birmingham, UK.
authors.forename: Melissa
authors.initials: M
authors.lastname: Nolen
authors.affiliation: Public Health, Epidemiology and Biostatistics, University of Birmingham, UK ; Institute of Public Health, Social and Preventive Medicine, Mannheim Medical Faculty, Heidelberg University, Mannheim, Germany.
authors.forename: G Neil
authors.initials: GN
authors.lastname: Thomas
authors.affiliation: Public Health, Epidemiology and Biostatistics, University of Birmingham, UK.
authors.forename: Paymanè
authors.initials: P
authors.lastname: Adab
authors.affiliation: Thoracic and Sleep Medicine Department, St Vincent's Hospital, Darlinghurst, Sydney, NSW, Australia ; NHMRC Centre for Integrated Research and Understanding Sleep (CIRUS), Woolcock Institute of Medical Research, University of Sydney, Glebe, Sydney, NSW, Australia.
authors.forename: Dev
authors.initials: D
authors.lastname: Banerjee
authors.affiliation: Department of Medicine, Weill Cornell Medical College New York, and Doha, Qatar ; Department of Medicine, King's College London, London, UK.
authors.forename: Shahrad
authors.initials: S
authors.lastname: Taheri
mesh_terms: D015992:Body Mass Index; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000453:epidemiology*; D017286:Polysomnography / Q000379:methods; D051436:Renal Insufficiency, Chronic / Q000453:epidemiology*; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*
keywords: diabetes mellitus; diabetes nephropathy; extreme obesity; obstructive sleep apnea; sleep disordered breathing