title: Accelerometer-derived sedentary and physical activity time in overweight/obese adults with type 2 diabetes: cross-sectional associations with cardiometabolic biomarkers.
abstract: OBJECTIVE
  To examine the associations of sedentary time and physical activity with biomarkers of cardiometabolic health, including the potential collective impact of shifting mean time use from less- to more-active behaviours (cross-sectionally, using isotemporal substitution), in adults with type 2 diabetes.
  
  
  METHODS
  Participants with overweight/obese body mass index (BMI; ≥25 kg/m2) (n = 279; 158 men, mean [SD] age = 58.2 [8.6] years) wore Actigraph GT1M accelerometers (waking hours; seven days) to assess moderate- to vigorous-intensity physical activity (MVPA), light-intensity activity, and sedentary time (segregated into non-prolonged [accumulated in bouts <30min] and prolonged [accumulated in bouts ≥30 min]). Cross-sectional associations with waist circumference, BMI, fasting blood (HbA1c, glucose, triacylglycerols, high-density lipoprotein cholesterol), and blood pressure of these activity variables (30 min/day increments) were examined adjusted for confounders and wear then, if significant, examined using isotemporal substitution modelling.
  
  
  RESULTS
  Waist circumference and BMI were significantly (p<0.05) associated with more prolonged sedentary time and less light-intensity activity. Light intensity activity was also significantly associated with lower fasting plasma glucose (relative rate: 0.98, 95% CI: 0.97, 1.00; p<0.05). No biomarker was significantly associated with non-prolonged sedentary time or MVPA. Lower mean prolonged sedentary time (-30 min/day) with higher mean light intensity time (+30 min/day) was significantly associated with lower waist circumference (β = -0.77, 95% CI: -1.33, -0.22 cm). Lower mean prolonged sedentary time (-30 min/day) with either 30 min/day higher mean non-prolonged sedentary time (β = -0.35, 95%CI: -0.70, -0.01 kg/m2) or light-intensity time (β = -0.36, -0.61, -0.11 kg/m2) was associated with significantly lower average BMI.
  
  
  CONCLUSIONS
  Significantly improved mean levels of waist circumference and BMI were observed when shifting time from prolonged sedentary to non-prolonged sedentary or light-intensity activity (cross-sectionally). Lifestyle interventions in overweight/obese adults with type 2 diabetes might consider targeting shifts in these non-MVPA activities to more rigorously evaluate their potential cardiometabolic benefit in this population.
authors.affiliation: The University of Queensland, School of Public Health, Brisbane, Australia; Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia; Curtin University, School of Physiotherapy, Perth, Western Australia, Australia.
authors.forename: Genevieve N
authors.initials: GN
authors.lastname: Healy
authors.affiliation: The University of Queensland, School of Public Health, Brisbane, Australia.
authors.forename: Elisabeth A H
authors.initials: EA
authors.lastname: Winkler
authors.affiliation: The University of Queensland, School of Public Health, Brisbane, Australia.
authors.forename: Charlotte L
authors.initials: CL
authors.lastname: Brakenridge
authors.affiliation: The University of Queensland, School of Public Health, Brisbane, Australia.
authors.forename: Marina M
authors.initials: MM
authors.lastname: Reeves
authors.affiliation: The University of Queensland, School of Public Health, Brisbane, Australia.
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Eakin
mesh_terms: D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001794:Blood Pressure; D002318:Cardiovascular Diseases / Q000097:blood / Q000453:epidemiology*; D008076:Cholesterol, HDL / Q000097:blood; D003430:Cross-Sectional Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D050177:Overweight / Q000097:blood / Q000150:complications* / Q000503:physiopathology; D057185:Sedentary Behavior; D014280:Triglycerides / Q000097:blood; D055105:Waist Circumference
chemical_list: D015415:Biomarkers; D001786:Blood Glucose; D008076:Cholesterol, HDL; D014280:Triglycerides