title: Cross-sectional and longitudinal associations between objectively measured sedentary time and metabolic disease: the Coronary Artery Risk Development in Young Adults (CARDIA) study.
abstract: OBJECTIVE
  Prolonged sedentary time (ST) might be contributing to the diabetes epidemic, but most studies have been cross-sectional and few have objectively measured ST. The purpose of this study was to evaluate cross-sectional and 5-year longitudinal relationships between ST and metabolic parameters and outcomes.
  
  
  METHODS
  This was an analysis of 2,027 Coronary Artery Risk Development in Young Adults (CARDIA) study participants (aged 38-50 years, 57% female, and mean BMI of 29.0 ± 7.0 kg/m(2)) with accelerometry data (≥4 days with ≥10 h/day) measured at the year 20 follow-up exam (2005-2006). Metabolic variables (fasting glucose, fasting insulin, 2-h postchallenge glucose, HOMA of insulin resistance [HOMA-IR], and HbA1c) and outcomes (impaired fasting glucose [IFG], impaired glucose tolerance [IGT], prediabetes by HbA1c, and diabetes) were assessed concurrently and 5 years later.
  
  
  RESULTS
  Average ST was 8.1 ± 1.7 h/day or 55 ± 10% of wear time. Each additional hour per day of ST was cross-sectionally associated with a 3% higher fasting insulin and HOMA-IR (both P < 0.01) but not 5-year changes in metabolic parameters. Having ≥10 h/day vs. <6 h/day of ST was associated with an odds ratio (OR) = 2.74 (95% CI 1.13, 6.62) for IGT and an OR = 3.80 (95% CI 1.39, 10.35) for diabetes. ST was not associated with prevalent IFG, prevalent prediabetes by HbA1c, or 5-year incidence of any metabolic outcomes (all P > 0.05).
  
  
  CONCLUSIONS
  ST was independently related to insulin, HOMA-IR, and prevalent diabetes and IGT but did not predict 5-year changes in metabolic parameters or incidence of metabolic outcomes. These results suggest that higher ST may not be a risk factor for future metabolic outcomes, but more research with repeated ST measurement and longer follow-up is needed.
authors.affiliation: Department of Health and Physical Activity, University of Pittsburgh, Pittsburgh, PA bbarone@pitt.edu.
authors.forename: Bethany
authors.initials: B
authors.lastname: Barone Gibbs
authors.affiliation: Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas Health Science Center at Houston, School of Public Health Austin Regional Campus, Austin, TX.
authors.forename: Kelley
authors.initials: K
authors.lastname: Pettee Gabriel
authors.affiliation: National Heart, Lung, and Blood Institute, Bethesda, MD.
authors.forename: Jared P
authors.initials: JP
authors.lastname: Reis
authors.affiliation: Department of Health and Physical Activity, University of Pittsburgh, Pittsburgh, PA.
authors.forename: John M
authors.initials: JM
authors.lastname: Jakicic
authors.affiliation: Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL.
authors.forename: Mercedes R
authors.initials: MR
authors.lastname: Carnethon
authors.affiliation: Department of Research, Kaiser Permanente Northern California, Oakland, CA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Sternfeld
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D003324:Coronary Artery Disease / Q000209:etiology* / Q000378:metabolism; D003430:Cross-Sectional Studies; D003925:Diabetic Angiopathies / Q000209:etiology / Q000378:metabolism; D015444:Exercise / Q000502:physiology; D005215:Fasting / Q000097:blood; D005260:Female; D018149:Glucose Intolerance / Q000378:metabolism; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008659:Metabolic Diseases / Q000209:etiology* / Q000378:metabolism; D011236:Prediabetic State / Q000378:metabolism; D012307:Risk Factors; D057185:Sedentary Behavior; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D007328:Insulin