title: Habitual shortened sleep and insulin resistance: an independent relationship in obese individuals.
abstract: OBJECTIVE
  Short sleep duration has been reported to be associated with obesity, type 2 diabetes, and pre-diabetes. Since excess weight, glucose abnormalities, and insulin resistance tend to cluster, the individual role insulin resistance may have in habitual shortened sleep is unclear. The study purpose was to assess whether habitual sleep curtailment is independently related to insulin resistance in obese individuals.
  
  
  METHODS
  Non-diabetic, overweight/obese individuals from the community were stratified as insulin-resistant (n=35) or insulin-sensitive (n=21) based on steady-state plasma glucose concentrations (SSPG) during the insulin suppression test. Seventy-five gram oral glucose tolerance tests were performed. Participants were asked, "On average, how many hours of sleep do you get per night?" Shortened sleep duration was defined as less than 7h of sleep per night.
  
  
  RESULTS
  SSPG concentrations differed 2.5-fold (P<0.001) between insulin-resistant and insulin-sensitive individuals. Impaired fasting glucose and glucose intolerance were prevalent in both groups (>40%); however, body mass index, waist circumference, mean fasting or 2-h post-glucola glucose concentrations were not significantly different. Insulin-resistant individuals reported (mean±SD) fewer hours of sleep than did insulin-sensitive individuals (6.53±1.1 vs. 7.24±0.9 h, P<0.05). Shortened sleep duration was more prevalent among insulin-resistant as compared with insulin-sensitive individuals (60% vs. 24%, P<0.05).
  
  
  CONCLUSIONS
  Non-diabetic, insulin-resistant individuals averaged fewer hours of sleep and were more likely to report shortened sleep duration as compared with similarly obese insulin-sensitive individuals. There appears to be an independent association between habitual shortened sleep and insulin resistance among obese, dysglycemic adults without diabetes.
authors.affiliation: Department of Medicine, Division of Endocrinology, Stanford University Medical Center, Stanford, CA 94305, USA. Electronic address: aliceliu@stanford.edu.
authors.forename: Alice
authors.initials: A
authors.lastname: Liu
authors.forename: Clete A
authors.initials: CA
authors.lastname: Kushida
authors.forename: Gerald M
authors.initials: GM
authors.lastname: Reaven
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000378:metabolism*; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000097:blood / Q000517:prevention & control; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000378:metabolism; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood; D050177:Overweight / Q000097:blood* / Q000378:metabolism / Q000503:physiopathology; D011236:Prediabetic State / Q000209:etiology / Q000378:metabolism; D012307:Risk Factors; D012890:Sleep; D011795:Surveys and Questionnaires; D013997:Time Factors
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin
keywords: Glucose intolerance; HOMA-IR; Homeostasis Model Assessment of Insulin Resistance; Insulin resistance; OSA; Obesity; SSPG; Sleep duration; T2DM; obstructive sleep apnea; steady-state plasma glucose; type 2 diabetes