title: Diabetes is an independent risk factor for severe nocturnal hypoxemia in obese patients. A case-control study.
abstract: BACKGROUND
  Type 2 diabetes mellitus (T2DM) and obesity have become two of the main threats to public health in the Western world. In addition, obesity is the most important determinant of the sleep apnea-hypopnea syndrome (SAHS), a condition that adversely affects glucose metabolism. However, it is unknown whether patients with diabetes have more severe SAHS than non-diabetic subjects. The aim of this cross-sectional case-control study was to evaluate whether obese patients with T2DM are more prone to severe SAHS than obese non-diabetic subjects.
  
  
  RESULTS
  Thirty obese T2DM and 60 non-diabetic women closely matched by age, body mass index, waist circumference, and smoking status were recruited from the outpatient Obesity Unit of a university hospital. The exclusion criteria included chronic respiratory disease, smoking habit, neuromuscular and cerebrovascular disease, alcohol abuse, use of sedatives, and pregnancy. Examinations included a non-attended respiratory polygraphy, pulmonary function testing, and an awake arterial gasometry. Oxygen saturation measures included the percentage of time spent at saturations below 90% (CT90). A high prevalence of SAHS was found in both groups (T2DM:80%, nondiabetic:78.3%). No differences in the number of sleep apnea-hypopnea events between diabetic and non-diabetic patients were observed. However, in diabetic patients, a significantly increase in the CT90 was detected (20.2+/-30.2% vs. 6.8+/-13,5%; p = 0.027). In addition, residual volume (RV) was significantly higher in T2DM (percentage of predicted: 79.7+/-18.1 vs. 100.1+/-22.8; p<0.001). Multiple linear regression analyses showed that T2DM but not RV was independently associated with CT90.
  
  
  CONCLUSIONS
  T2DM adversely affects breathing during sleep, becoming an independent risk factor for severe nocturnal hypoxemia in obese patients. Given that SAHS is a risk factor of cardiovascular disease, the screening for SAHS in T2DM patients seems mandatory.
authors.affiliation: CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Instituto de Salud Carlos III (ISCIII), Diabetes and Metabolism Research Unit, Institut de Recerca Hospital Universitari Vall d'Hebron, Barcelona, Spain. alecube@vhebron.net
authors.forename: Albert
authors.initials: A
authors.lastname: Lecube
authors.forename: Gabriel
authors.initials: G
authors.lastname: Sampol
authors.forename: Patricia
authors.initials: P
authors.lastname: Lloberes
authors.forename: Odile
authors.initials: O
authors.lastname: Romero
authors.forename: Jordi
authors.initials: J
authors.lastname: Mesa
authors.forename: Cristina
authors.initials: C
authors.lastname: Hernández
authors.forename: Rafael
authors.initials: R
authors.lastname: Simó
mesh_terms: D016022:Case-Control Studies; D048909:Diabetes Complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D009765:Obesity / Q000150:complications*; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000209:etiology*