I. Diagnostic Criteria

The 2003 Rotterdam diagnostic criteria for PCOS jointly established by the European Society of Human Reproduction and Embryology (ESHRE) and the American Society for Reproductive Medicine (ASRM):

Clinical and/or biochemical signs of hyperandrogenism; Oligo-ovulation or anovulation; Ultrasound findings: ovarian volume ≥ 10 mL, and/or > 12 follicles with a diameter of 2-9 mm in a single section.

A diagnosis of PCOS can be established when at least two of the following three criteria are met: ovarian dysfunction, hyperandrogenism, and polycystic ovarian morphology on ultrasound.

II. Inclusion and Exclusion Criteria

1. PCOS with Insulin Resistance (PCOS-IR)

   Inclusion Criteria:

   Meets the 2003 Rotterdam diagnostic criteria for PCOS (at least 2 of the following 3 items):

   ① Oligo-ovulation or anovulation;

   ② Clinical or biochemical signs of hyperandrogenism;

   ③ Polycystic ovaries on ultrasound (unilateral or ovarian volume ≥ 10 mL).

   Insulin resistance (IR), meeting at least 1 of the following 3 criteria:

   ① HOMA-IR ≥ 2.5;

   ② Fasting insulin ≥ 15 μIU/mL;

   ③ Diagnosed impaired glucose tolerance (IGT) or type 2 diabetes mellitus (T2DM).

   Exclusion Criteria:

   Other endocrine disorders; Medication effects; Severe systemic diseases; Special physiological conditions (e.g., pregnancy, lactation); Poor sample quality.

2. PCOS without Insulin Resistance (PCOS-non-IR)

Inclusion Criteria:

Meets the PCOS diagnostic criteria (as above), with HOMA-IR < 2.5 and no glucose metabolism abnormalities.

Exclusion Criteria: Same as above.