title: Objectively measured sedentary time and associations with insulin sensitivity: Importance of reallocating sedentary time to physical activity.
abstract: OBJECTIVE
  The aim of this study is to quantify associations between objectively measured sedentary time and markers of insulin sensitivity by considering allocation into light-intensity physical activity or moderate- to vigorous-intensity physical activity (MVPA).
  
  
  METHODS
  Participants with an increased risk of impaired glucose regulation (IGR) were recruited (Leicestershire, United Kingdom, 2010-2011). Sedentary, light-intensity physical activity and MVPA time were measured using accelerometers. Fasting and 2-hour post-challenge insulin and glucose were assessed; insulin sensitivity was calculated by HOMA-IS and Matsuda-ISI. Isotemporal substitution regression models were used. Data were analysed in 2014.
  
  
  RESULTS
  508 participants were included (average age=65years, female=34%). Reallocating 30min of sedentary time into light-intensity physical activity was associated a 5% (95% CI 1, 9%; p=0.024) difference in Matsuda-ISI after adjustment for measured confounding variables. Reallocation into MVPA was associated with a 15% (7, 25%; p<0.001) difference in HOMA-IS and 18% (8, 28%; p<0.001) difference in Matsuda-ISI. Results for light-intensity physical activity were modified by IGR status with stronger associations seen in those with IGR.
  
  
  CONCLUSIONS
  Reallocating sedentary time into light-intensity physical activity or MVPA was associated with differences in insulin sensitivity, with stronger and more consistent associations seen for MVPA.
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Yates
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Henson
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, UK. Electronic address: ce95@le.ac.uk.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Edwardson
authors.affiliation: Physical Activity Laboratory, Baker IDI Heart and Diabetes Institute, Melbourne, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Dunstan
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, UK.
authors.forename: Danielle H
authors.initials: DH
authors.lastname: Bodicoat
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Collaboration for Leadership in Applied Health Research and Care-East Midlands (NIHR CLAHRC-EM), UK.
authors.forename: Kamlesh
authors.initials: K
authors.lastname: Khunti
authors.affiliation: Diabetes Research Centre, College of Medicine, Biological Sciences and Psychology, University of Leicester, Leicester, UK; NIHR Leicester-Loughborough Diet, Lifestyle, and Physical Activity Biomedical Research Unit, UK.
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Davies
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D002318:Cardiovascular Diseases / Q000209:etiology; D015444:Exercise / Q000502:physiology*; D005215:Fasting; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D057185:Sedentary Behavior; D006113:United Kingdom
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D007328:Insulin
keywords: Glucose; Insulin sensitivity; Isotemporal substitution; Physical activity; Sedentary behaviour