Efficacy and Safety of Metformin in Preventing Patients With Risperidone From Weight Gain and Amenorrhea

Inclusion Criteria: 1. age 18-40 years. 2. diagnosis of schizophrenia (naive first-episode) as defined in DSM-IV axis I. 3. At screening, patients were required to have total score ≥60 on Positive and Negative Syndrome Scale (PANSS) and ≥4 on the Clinical Global Impression-severity scale (CGI-S). 4. treat with Risperidone. 5. Never participate in a diet control nor in other weight loss programs, and have a normal Period. 6. Written informed consents could be obtained from patients(or their Legal guardian). Exclusion Criteria: 1. Female patients, those who were in the period of pregnancy and lactation, or plan pregnancy, were excluded. 2. Patients with serious physical disease patients, just like Epilepsy, liver and kidney dysfunction, diabetes, blood diseases, etc were excluded. 3. At screening, patients with abnormal results in physical examination, laboratory test, or electrocardiogram (ECG) were excluded. 4. Patients were also excluded if they met primary DSM-IV axis I psychiatric disorders other than schizophrenia, or ever used psychoactive substance.