To study the effects of pioglitazone combined with metformin and metformin on gonadal and metabolic profiles in PCOS patients with BMI < 24 in China. 60 cases of nonobese PCOS patients were collected from Shengjing hospital. The intervention period was 3 months after intervention with met or met + ph. To evaluate the improvement of met or met + ph in the treatment of hyperandremia, glucose metabolism, BMI, waist circumference, menstruation, hairiness and acne in PCOS patients.

Inclusion Criteria:

1. Females 18 years to 40 years of age Diagnosed as PCOS by the 2003 Rotterdam criteria
2. BMI<24 kg/m2
3. No pregnant plan in recent 6 months
4. Written consent for participation in the study

Exclusion Criteria:

1. type 1 or type 2 diabetes mellitus

2. Subjects have other endocrine diseases, such as adrenal hyperplasias or tumor, androgen-secreting tumors, Cushing's syndrome, thyroid diseases, and hyperprolactinemia

3. Diagnosed with or have a family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)

4. Serious systemic disease or malignant tumor

5. History of pancreatitis (chronic, acute or recurrent)

6. Body weight change ≥10% at 3 months before treatment

7. Used oral contraceptives or sex hormone drugs in the past 1 month

8. Used oral glucocorticoids in the past 1 month

9. Substance (alcohol or drug) abuse or dependence within 3 months

10. Heavy smokers (smokers who smoke 20 or more cigarettes a day) or heavy drinkers (>10g/d)

11. Subjects have a severe systemic disease, such as cardiovascular system, Renal impairment (eGFR<60ml/min/1.73m2)

12. Increase of transaminases up to < 2.5 times of upper limit of normal value

13. Have a history of thromboembolic disease or thrombotic tendency

14. Subjects in pregnant or lactating or within 1 year after delivery

15. Subjects have an allergic history to the drugs used in the study

16. Subjects have participated in other clinical researches of medicine within

    1 month prior to randomization

17. Use of metformin, pioglitazone, or pioglitazone combined with metformin within 30 days before screening