title: Changes in insulin resistance and HbA1c are related to exercise-mediated changes in body composition in older adults with type 2 diabetes: interim outcomes from the GREAT2DO trial.
abstract: OBJECTIVE
  To investigate changes in body composition after 12 months of high-intensity progressive resistance training (PRT) in relation to changes in insulin resistance (IR) or glucose homeostasis in older adults with type 2 diabetes.
  
  
  METHODS
  One-hundred three participants were randomized to receive either PRT or sham exercise 3 days per week for 12 months. Homeostasis model assessment 2 of insulin resistance (HOMA2-IR) and glycosylated hemoglobin (HbA1c) were used as indices of IR and glucose homeostasis. Skeletal muscle mass (SkMM) and total fat mass were assessed using bioelectrical impedance. Visceral adipose tissue, mid-thigh cross-sectional area, and mid-thigh muscle attenuation were quantified using computed tomography.
  
  
  RESULTS
  Within the PRT group, changes in HOMA2-IR were associated with changes in SkMM (r = -0.38; P = 0.04) and fat mass (r = 0.42; P = 0.02). Changes in visceral adipose tissue tended to be related to changes in HOMA2-IR (r = 0.35; P = 0.07). Changes in HbA1c were related to changes in mid-thigh muscle attenuation (r = 0.52; P = 0.001). None of these relationships were present in the sham group (P > 0.05). Using ANCOVA models, participants in the PRT group who had increased SkMM had decreased HOMA2-IR (P = 0.05) and HbA1c (P = 0.09) compared with those in the PRT group who lost SkMM. Increases in SkMM in the PRT group decreased HOMA2-IR (P = 0.07) and HbA1c (P < 0.05) compared with those who had increased SkMM in the sham group.
  
  
  CONCLUSIONS
  Improvements in metabolic health in older adults with type 2 diabetes were mediated through improvements in body composition only if they were achieved through high-intensity PRT.
authors.affiliation: Exercise Health and Performance Faculty Research Group, Faculty of Health Sciences, University of Sydney, Sydney, Australia. yorgi.mavros@sydney.edu.au
authors.forename: Yorgi
authors.initials: Y
authors.lastname: Mavros
authors.forename: Shelley
authors.initials: S
authors.lastname: Kay
authors.forename: Kylie A
authors.initials: KA
authors.lastname: Anderberg
authors.forename: Michael K
authors.initials: MK
authors.lastname: Baker
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Renru
authors.initials: R
authors.lastname: Zhao
authors.forename: Jacinda
authors.initials: J
authors.lastname: Meiklejohn
authors.forename: Mike
authors.initials: M
authors.lastname: Climstein
authors.forename: Anthony
authors.initials: A
authors.lastname: O'Sullivan
authors.forename: Nathan
authors.initials: N
authors.lastname: de Vos
authors.forename: Bernhard T
authors.initials: BT
authors.lastname: Baune
authors.forename: Steven N
authors.initials: SN
authors.lastname: Blair
authors.forename: David
authors.initials: D
authors.lastname: Simar
authors.forename: Kieron
authors.initials: K
authors.lastname: Rooney
authors.forename: Nalin
authors.initials: N
authors.lastname: Singh
authors.forename: Maria A
authors.initials: MA
authors.lastname: Fiatarone Singh
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000534:rehabilitation; D006442:Glycated Hemoglobin / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008954:Models, Biological; D055070:Resistance Training
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin