Study Design: Double- Masked Randomized Clinical Trial. The follow up period estimated is 12 months after the last PRP section. Patients enrollment: Thirty patients with severe nonproliferative or early proliferative diabetic retinopathy and no previous laser treatment were enrolled. They were divided into two groups: "A" which received Copaxone or "B"which received mannitol (placebo) using a block randomization. Both drugs were offered by subcutaneous administration one week prior and in the three sections of PRP, one per week. All patients received and signed a written inform consent approved by the research ethics committee of UNIFESP.