Conclusions
We demonstrate evidence of complement activation and dysregulation in women with PCOS which is exacerbated in the presence of obesity and insulin resistance. We show that this extends to the terminal pathway and is evident in the postprandial as well as the fasting state. These disturbances have implications for lipid clearance, inflammation and insulin sensitivity, and suggest that interventions aimed at regulating complement activation in PCOS may be helpful in reducing cardiometabolic risk.