At the core of PCOS lies a disrupted relationship between insulin and reproductive hormones. In healthy metabolic function, insulin efficiently escorts glucose from the bloodstream into cells for energy. In PCOS, up to 70 percent of affected women develop insulin resistance, meaning their cells respond poorly to insulin signals, forcing the pancreas to produce excess insulin to compensate. The Office on Women's Health identifies PCOS as a leading cause of infertility and metabolic complications in women.
This compensatory hyperinsulinemia directly stimulates the ovaries to produce excessive androgens, the male hormones like testosterone that drive many PCOS symptoms. Elevated insulin also increases luteinizing hormone (LH) pulse frequency from the pituitary gland, further amplifying ovarian androgen production and creating a self-perpetuating cycle of hormonal imbalance.
The excess androgens disrupt normal follicular development in the ovaries, preventing eggs from maturing and releasing properly. This leads to the characteristic string-of-pearl appearance of multiple small follicles on ultrasound, irregular ovulation, and the downstream effects of menstrual irregularity, acne, hair thinning, and excess body hair. The resulting weight gain that many women with PCOS experience further compounds these hormonal disruptions.
