The relation of body fat mass and distribution to markers of chronic inflammation.
OBJECTIVE
To study the relation of fibrinogen and C-reactive protein (CRP) to various measures of body fat and body fat distribution and to investigate whether these relations were explained by differences in insulin sensitivity.


METHODS
Cross-sectional analysis of the IRAS (Insulin Resistance Atherosclerosis Study), a large (n=1559) tri-ethnic population (non-Hispanic whites, African-Americans and Mexican-Americans) across different states of glucose tolerance.


METHODS
Glucose tolerance (oral glucose tolerance test), insulin sensitivity (frequently sampled intravenous glucose tolerance test and minimal model analysis), assessment of body fat mass and distribution (weight, girths, bioelectrical impedance), subclinical atherosclerosis (B-mode ultrasonography of carotid artery intima-media thickness, IMT), CRP (highly sensitive immunoassay), fibrinogen (standard assay).


RESULTS
Both CRP and fibrinogen were related to all measures of body fat. Strong correlations (correlation coefficient r > or = 0.35) were found between CRP and body mass index (BMI), waist circumference and adipose body mass, respectively. The associations were consistent in non-diabetic and type-2 diabetic subjects, were generally stronger in women, and were only moderately attenuated by the prevailing insulin sensitivity (S(I)). In a multivariate linear regression model waist circumference explained 14.5% of the variability of circulating CRP levels (P=0.0001), BMI 0.4% (P=0.0067), and S(I) 1.7% (P=0.0001). Common carotid artery IMT was related to CRP and fibrinogen in men, but not in women, and was attenuated after adjusting for BMI or waist.


CONCLUSIONS
Our findings show that measures of body fat are strongly associated with circulating levels of CRP and fibrinogen. These associations were not explained by lower S(I) in obese subjects. Chronic, subclinical inflammation may be one pathophysiological mechanism explaining the increased risk of atherosclerotic disease associated with adiposity.
Festa
A
A
Department of Medicine, Division of Clinical Epidemiology, University of Texas Health Science Center at San Antonio, Texas, USA.
D'Agostino
R
R
Williams
K
K
Karter
A J
AJ
Mayer-Davis
E J
EJ
Tracy
R P
RP
Haffner
S M
SM
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D000368:Aged; D001161:Arteriosclerosis / Q000097:blood / Q000276:immunology* / Q000473:pathology; D015415:Biomarkers / Q000097:blood; D001823:Body Composition; D001824:Body Constitution; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis*; D002339:Carotid Arteries / Q000473:pathology; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D005260:Female; D005340:Fibrinogen / Q000032:analysis*; D005951:Glucose Tolerance Test; D006801:Humans; D007249:Inflammation; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000276:immunology; D012737:Sex Factors
D015415:Biomarkers; D007328:Insulin; D005340:Fibrinogen; D002097:C-Reactive Protein