title: Dietary weight loss and exercise effects on insulin resistance in postmenopausal women.
abstract: BACKGROUND
  Comprehensive lifestyle interventions are effective in preventing diabetes and restoring glucose regulation; however, the key stimulus for change has not been identified and effects in older individuals are not established. The aim of the study was to investigate the independent and combined effects of dietary weight loss and exercise on insulin sensitivity and restoration of normal fasting glucose in middle-aged and older women.
  
  
  METHODS
  Four-arm RCT, conducted between 2005 and 2009 and data analyzed in 2010.
  
  
  METHODS
  439 inactive, overweight/obese postmenopausal women.
  
  
  METHODS
  Women were assigned to: dietary weight loss (n=118); exercise (n=117); exercise+diet (n=117); or control (n=87). The diet intervention was a group-based reduced-calorie program with a 10% weight-loss goal. The exercise intervention was 45 min/day, 5 days/week of moderate-to-vigorous intensity aerobic activity.
  
  
  METHODS
  12-month change in serum insulin, C-peptide, fasting glucose, and whole body insulin resistance (HOMA-IR).
  
  
  RESULTS
  A significant improvement in HOMA-IR was detected in the diet (-24%, p<0.001) and exercise+ diet (-26%, p<0.001) groups but not in the exercise (-9%, p=0.22) group compared with controls (-2%); these effects were similar in middle-aged (50-60 years) and older women (aged 60-75 years). Among those with impaired fasting glucose (5.6-6.9 mmol/L) at baseline (n=143; 33%), the odds (95% CI) of regressing to normal fasting glucose after adjusting for weight loss and baseline levels were 2.5 (0.8, 8.4); 2.76 (0.8, 10.0); and 3.1 (1.0, 9.9) in the diet, exercise+diet, and exercise group, respectively, compared with controls.
  
  
  CONCLUSIONS
  Dietary weight loss, with or without exercise, significantly improved insulin resistance. Older women derived as much benefit as did the younger postmenopausal women.
  
  
  BACKGROUND
  This study is registered at Clinicaltrials.govNCT00470119.
authors.affiliation: Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
authors.forename: Caitlin
authors.initials: C
authors.lastname: Mason
authors.forename: Karen E
authors.initials: KE
authors.lastname: Foster-Schubert
authors.forename: Ikuyo
authors.initials: I
authors.lastname: Imayama
authors.forename: Angela
authors.initials: A
authors.lastname: Kong
authors.forename: Liren
authors.initials: L
authors.lastname: Xiao
authors.forename: Carolyn
authors.initials: C
authors.lastname: Bain
authors.forename: Kristin L
authors.initials: KL
authors.lastname: Campbell
authors.forename: Ching-Yun
authors.initials: CY
authors.lastname: Wang
authors.forename: Catherine R
authors.initials: CR
authors.lastname: Duggan
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Ulrich
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Alfano
authors.forename: George L
authors.initials: GL
authors.lastname: Blackburn
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
mesh_terms: D000367:Age Factors; D000368:Aged; D001786:Blood Glucose; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D004038:Diet, Reducing; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance / Q000502:physiology*; D008019:Life Style; D008875:Middle Aged; D017698:Postmenopause; D015431:Weight Loss
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin