Differentiation between obesity and insulin resistance in the association with C-reactive protein

Background-Plasma C-reactive protein (CRP) concentrations are increased in obese and/or hyperinsulinemic individuals. The goal of this study was to determine if the relation between insulin resistance and CRP was independent of obesity. Methods and Results-Plasma CRP concentrations were measured before and after 3 months of calorie restriction in 38 healthy, obese women. Steady-state plasma glucose (SSPG) concentration during a 180-minute infusion of octreotide, glucose, and insulin was used to stratify participants into insulin-resistant (IR, n = 20) or insulin-sensitive (n = 18) groups, similar in terms of mean age (46 +/- 2 versus 44 +/- 2 years), body mass index (32.0 +/- 0.4 versus 31.4 +/- 0.3 kg/m(2)), and waist circumference (96 +/- 2 versus 95 +/- 2 cm). Mean CRP (0.39 +/- 0.08 versus 0.12 +/- 0.03 mg/dL, P = 0.003) concentrations were higher in the IR group, as were day-long plasma glucose and insulin responses (P < 0.001). There was a significant correlation at baseline between CRP and day-long plasma integrated insulin response (r = 0.47, P = 0.001) but not between CRP and body mass index (r = 0.14) or waist circumference (r = 0.10). Weight loss was similar in the two groups (8.7 +/- 0.9 versus 8.4 +/- 0.8 kg) but was associated with significant (P < 0.001) decreases in SSPG and CRP concentrations in the IR group only. Regression analysis showed that SSPG and day-long plasma insulin response were the only significant predictors of CRP concentration. Conclusions-CRP concentrations are elevated predominantly in obese individuals who are also insulin resistant and fall in parallel with weight loss-associated improvements in insulin resistance. The relation between CRP concentrations and insulin resistance is independent of obesity.