Serum complement C3 has a stronger association with insulin resistance than high-sensitivity C-reactive protein in women with polycystic ovary syndrome.

Objective: To compare the association of complement C3 (C3) versus high-sensitivity C-reactive protein (hs-CRP) with insulin resistance (IR) in women with polycystic ovary syndrome (PCOS).

Design: Cross-sectional analysis.

Setting: Clinical research center in China.

Patient(s): One hundred thirty-three women with PCOS and 116 healthy, age-matched controls were recruited.

Intervention(s): None.

Main Outcome Measure(s): One hundred one women with PCOS and 20 controls underwent hyperinsulinemic-euglycemic clamp to assess their insulin sensitivity, which was expressed as an M value.

Result(s): Compared with controls, women with PCOS had a lower M value and higher C3 (1.37 ± 0. 34 vs. 1.10 ± 0.22 g/L) and hs-CRP levels (1.46 ± 2.29 vs. 0.49 ± 0.88 mg/L). In women with PCOS, C3 and hs-CRP negatively correlated with M value (r = -0.61 and r = -0.47, respectively). By regression analysis, C3 was found to have a greater impact on the M value (standardized coefficient β = -0.24) than did hs-CRP (standardized coefficient β = -0.13). After adjusting for body mass index (BMI), women with PCOS in the upper quartile were 4.30 times more likely to exhibit IR compared with those in the lower quartiles, whereas hs-CRP was not a statistically significant predictor of IR in women with PCOS.

Conclusion(s): Compared with hs-CRP, serum C3 might be a stronger inflammatory marker of IR in women with PCOS.