IL18 and polycystic ovary syndrome: The serum levels of IL-18 in the PCOS group were significantly higher. Furthermore, PCOS patients with insulin resistance (IR) and obesity had higher serum IL-18 levels, suggesting that IR and obesity may accelerate the increase in serum IL-18 levels. The study also found that IL-18 was positively correlated with BMI, IR, and testosterone (T).