title: Relationships of insulin sensitivity with fatness and fitness and in older men and women.
abstract: OBJECTIVE
  Increased body fatness, especially abdominal obesity, and low levels of fitness are associated with decreased insulin sensitivity. Men and women differ in obesity, body fat distribution, and fitness levels. This cross-sectional study evaluated sex differences in the relationships of insulin sensitivity with fatness and fitness and obesity.
  
  
  METHODS
  Subjects were nonsmoking, nondiabetic, sedentary men (n = 50) and women (n = 61) aged 55-75 years with mild hypertension. Study measures were insulin sensitivity (QUICKI: 1/[log(fasting insulin) + log(fasting glucose)]), lipids and lipoproteins, total body fatness using dual energy x-ray absorptiometry (DXA), anthropometrics, abdominal obesity using magnetic resonance imaging (MRI), and aerobic fitness assessed as Vo(2) peak during treadmill testing.
  
  
  RESULTS
  Women had a higher percentage of body fat and more abdominal subcutaneous and less visceral fat than men. Among women, QUICKI correlated negatively with body mass index (BMI), percent body fat, abdominal total fat, subcutaneous fat, and visceral fat but not with lipids. Among men, QUICKI correlated negatively with total and abdominal fatness and triglycerides. QUICKI correlated with fitness in men only. Using stepwise regression, among women, decreased total abdominal fat accounted for 33%, and postmenopausal hormone therapy accounted for an additional 5% of the variance in QUICKI. Among men, only a higher level of fitness independently correlated with insulin sensitivity, accounting for 21% of the variance (p < 0.01).
  
  
  CONCLUSIONS
  Abdominal obesity among women and fitness among men were the strongest determinants of insulin sensitivity in this older cohort. This raises the question whether there are sex differences in the lifestyle changes that would be most effective in improving insulin sensitivity.
authors.affiliation: Division of Cardiology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland 21224, USA. pouyang@jhmi.edu
authors.forename: Pamela
authors.initials: P
authors.lastname: Ouyang
authors.forename: Jidong
authors.initials: J
authors.lastname: Sung
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kelemen
authors.forename: Paul S
authors.initials: PS
authors.lastname: Hees
authors.forename: James R
authors.initials: JR
authors.lastname: DeRegis
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Turner
authors.forename: Anita C
authors.initials: AC
authors.lastname: Bacher
authors.forename: Kerry J
authors.initials: KJ
authors.lastname: Stewart
mesh_terms: D000005:Abdomen / Q000503:physiopathology; D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000368:Aged; D001823:Body Composition; D001824:Body Constitution; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications / Q000378:metabolism*; D010809:Physical Fitness; D012044:Regression Analysis; D012307:Risk Factors; D012737:Sex Factors
chemical_list: D008055:Lipids; D008074:Lipoproteins