Relationships of insulin sensitivity with fatness and fitness and in older men and women.
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.
Ouyang
Pamela
P
Division of Cardiology, Johns Hopkins Bayview Medical Center, Baltimore, Maryland 21224, USA. pouyang@jhmi.edu
Sung
Jidong
J
Kelemen
Mark D
MD
Hees
Paul S
PS
DeRegis
James R
JR
Turner
Katherine L
KL
Bacher
Anita C
AC
Stewart
Kerry J
KJ
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
D008055:Lipids; D008074:Lipoproteins