The girls were from the normal-weight groups in the RESISTANT (resistance to insulin in type 1 and type 2 diabetes) study and AIRS (androgens and insulin resistance study) [3 (link), 4 (link), 18 (link)]. The inclusion criteria were female sex, nonobese BMI (≤90th percentile), age 12 to 20 years, and sedentary status (<3 h/wk of exercise). Sedentary status was confirmed using a 3-day activity recall questionnaire (3DPAR) and the use of an accelerometer for 7 days, because activity can independently affect the measurements of IS. The exclusion criteria were diabetes mellitus, alanine transferase >80 IU/mL, blood pressure >140/90 mm Hg, hemoglobin <9 mg/dL, serum creatinine >1.5 mg/dL, smoking, medications affecting IS, antihypertensive medications, statins, pregnancy, and breastfeeding. PCOS was defined using the National Institutes of Health (NIH) criteria of oligomenorrhea and clinical and/or biochemical evidence of hyperandrogenism and ≥2 years after menarche [19 , 20 ]. PCO morphology was not assessed owing to the lack of normative standards for youth [20 ]. The University of Colorado Anschutz Medical Campus institutional review board and the Children’s Hospital of Colorado scientific advisory review committee approved the present study. All participants aged 18 to 20 years provided written informed consent, and the parents and participants provided consent and assent, respectively, for all participants aged <18 years.