Association between complement component C3 and body composition: a possible obesity inflammatory biomarker for insulin resistance.

BACKGROUND AND OBJECTIVES The C3 complement component (C3) is increasingly recognized as a cardiometabolic risk factor. We aimed to examine the role of C3 in insulin resistance (IR) and its association with adiposity. METHODS AND STUDY DESIGN Sixty-seven obese (18-35 years) participants were matched with normal weight participants from the University of Jordan. BMI, waist-hip ratio (WHpR), and waist-height ratio (WHtR) were calculated. Body percent fat mass (%FM) was determined using the bioelectrical impedance analysis. C3, insulin, and glucose serum concentrations were measured. IR was assessed by the homeostasis model assessment of IR (HOMA-IR). RESULTS Serum concentrations of C3 and IR were significantly higher in the obese group than that in the normal body weight, regardless of gender (women: 1.2±0.08 and men: 1.2±0.08 vs women: 0.88±0.07 and men: 0.94±0.05, p<0.01; women: 3.6±0.34 and men: 3.9±0.43 vs women: 1.7±0.12 and men: 2.0±0.24, respectively; p<0.001). After adjustment for the potential confounders, BMI, waist circumference, WHtR and %FM were correlated positively with C3 (r=0.44; 0.42; 0.47; 0.43, respectively; p<0.001), and with IR (r=0.67; 0.61; 0.59; 0.59, respectively; p<0.001). C3 was correlated with IR (r=0.35, p<0.001). In linear regression analysis, C3 was not associated with IR independent of BMI (p>0.05). CONCLUSIONS C3 may be a marker of chronic inflammatory process independently underlying IR obese individuals regardless of gender, which may have a role in the progression of IR during obesity.