This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Polycystic ovary syndrome (PCOS) affects 5-10% of reproductive-aged women worldwide, resulting in chronic anovulation and an accelerated onset of type 2 diabetes and its precursors. We hypothesize that aberrant insulin action precedes and facilitates the reproductive dysfunction seen in adult PCOS. We will contrast the patterns of insulin sensitivities throughout puberty in girls from families with documented PCOS, with and without associated glucose intolerance, to determine whether pubertal disorders of insulin action predict eventual expression of PCOS.