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 investiga te whether these relations were explained by differences in insulin sensiti vity. DESIGN AND SUBJECTS: Cross-sectional analysis of the MAS (insulin Resistanc e Atherosclerosis Study), a large (n = 1559) triethnic population (non-Hisp anic whites, African-Americans and Mexican-Americans) across different stat es of glucose tolerance. MEASUREMENTS: Glucose tolerance (oral glucose tolerance test), insulin sens itivity (frequently sampled intravenous glucose tolerance test and minimal model analysis), assessment of body fat mass and distribution (weight, girt hs, bioelectrical impedance), subclinical atherosclerosis (B-mode ultrasono graphy of carotid artery intima-media thickness, IMT), CRP (highly sensitiv e immunoassay), fibrinogen (standard assay). RESULTS: Both CRP and fibrinogen were related to all measures of body fat. Strong correlations (correlation coefficient r greater than or equal to 0.3 5) were found between CRP and body mass index (BMI), waist circumference an d adipose body mass, respectively. The associations were consistent in non- diabetic and type-2 diabetic subjects, were generally stronger in women, an d were only moderately attenuated by the prevailing insulin sensitivity (SI ). 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, 1.7% (P=0.0001). Common carotid artery IMT was related to C RP and fibrinogen in men, but not in women, and was attenuated after adjust ing for BMI or waist. CONCLUSION: Our findings show that measures of body fat are strongly associ ated with circulating levels of CRP and fibrinogen. These associations were not explained by lower S, in obese subjects. Chronic, subclinical inflamma tion may be one pathophysiological mechanism explaining the increased risk of atherosclerotic disease associated with adiposity.