Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in reproductive-age women, and it affects 5-7% of this group. It is characterized by disturbed menstrual cycle, ovulatory dysfunction and hyperandrogenism. Over 40% of PCOS women might become the patients with impaired glucose tolerance or type 2 diabetes. It has been confirmed that insulin resistance (IR) is a common feature in PCOS and adipokines might play roles in the pathogenesis of IR and PCOS, because these adipokines have wide-ranging effects on carbohydrate and lipid metabolism.

The present clinical trial intends to compare the effects of metformin and oral contraceptives on PCOS patients, focusing on the insulin sensitivity, ovulation, and menstrual cycle etc. The investigators also aim to study the effects of metformin on serum adipokine levels(such as pigment epithelium-derived factor, progranulin etc.)in PCOS patients.

Inclusion Criteria:

with at least two of the following features : (i) oligo-amenorrhea or chronic anovulation; (ii) clinical and/or biochemical hyperandrogenism; (iii) ultrasound appearance of polycystic ovaries

Exclusion Criteria:

- other known causes of hyperandrogenemia and ovulatory dysfunction, including 21-hydroxylase deficiency, congenital adrenal hyperplasia, Cushing's syndrome, androgen-secreting tumors, thyroid disease, and hyperprolactinemia.

use of hormone medications (including oral contraceptives) within the past month and the use of medicines that affect insulin sensitivity (e.g., metformin or thiazolidinediones) within the past three months