Phase IIIb, multicenter, open-label, prospective, interventional study to assess the potential benefit of Aflibercept treatment administered IVT at a dosage of 2 mg with five monthly loading doses and then treat and extend over 48 weeks, with the primary endpoint as BCVA assessed at Week 52.

Inclusion Criteria:

• Adults ≥ 20 years old with type 1 or 2 diabetes mellitus
• Subjects with DME secondary to diabetes mellitus involving the center of the macula (defined as the area of the center subfield of optical coherence tomography [OCT]) in the study eye
• Retinal thickness as assessed by OCT above (>) 300 um in the study eye
• BCVA ETDRS letter score of 73 to 24 (20/40 to 20/320) in the study eye
• Would be able to comply with clinic visits and study-related procedures
• Would be able to provide a signed informed consent form (ICF)

Exclusion Criteria:

1. Ocular conditions with a poorer prognosis in the fellow eye than in the study eye

2. History of vitreoretinal surgery and/or including scleral buckling in the study eye

3. Laser photocoagulation (pan-retinal or macular) in the study eye within 90 days of Day 1

4. Against the background of a relevant number of previous macular laser treatments the investigator's point of view was that the subjects had no potential to benefit from laser treatments (e.g., if too many laser treatments were applied in the past)

5. Previous use of intraocular or periocular corticosteroids in the study eye within 120 days of Day 1

6. Previous treatment with anti-angiogenic drugs in either eye (pegaptanib sodium, bevacizumab, ranibizumab etc.) within 90 days of Day 1

7. High risk proliferative diabetic retinopathy (PDR) in the study eye upon physician's discretion

   High risk = the presence of any of the following:

   • Vitreous hemorrhage
   • New vessels on the disk >1/3 disk diameter
   • New vessels elsewhere >1/2 disk diameter

8. History of idiopathic or autoimmune uveitis in the study eye

9. Cataract surgery within 90 days before Day 1 in the study eye

10. Aphakia in the study eye

11. Yttrium-aluminium-garnet (YAG) capsulotomy in the study eye within 30 days before Day 1

12. Any other intraocular surgery within 90 days of Day 1 in the study eye

13. Vitreomacular traction or epiretinal membrane in the study eye evident biomicroscopically or on OCT that is thought to affect central vision

14. Current iris neovascularization, vitreous hemorrhage, or tractional retinal detachment in the study eye

15. Pre-retinal fibrosis involving the macula in the study eye

16. Structural damage to the center of the macula in the study eye that was likely to preclude improvement in BCVA following the resolution of macular edema including atrophy of the retinal pigment epithelium, subretinal fibrosis or scar, significant macular ischemia or organized hard exudates

17. Ocular inflammation including trace or above in the study eye

18. Evidence of infectious blepharitis, keratitis, scleritis, or conjunctivitis in either eye

19. Filtration surgery for glaucoma in the past or likely to be needed in the future on the study eye

20. Intraocular pressure (IOP) ≥ 25 mmHg in the study eye

21. High myopia (≤ -6.0 diopters or axial length of ≥26.5 mm) prior to any possible refractive or cataract surgery

22. Concurrent disease in the study eye, other than DME, that could compromise VA, require medical or surgical intervention during the study period, or could confound interpretation of the results (including retinal vascular occlusion, retinal detachment, macular hole, or choroidal neovascularization of any cause)

23. Only 1 functional eye even if that eye was otherwise eligible for the study

24. Ocular media of insufficient quality to obtain fundus and OCT images

25. Current treatment for a serious systemic infection

26. Administration of systemic anti-angiogenic agents within 180 days before Day 1

27. Uncontrolled diabetes mellitus, as defined by Hemoglobin A1c; (glycosylated hemoglobin) (HbA1c)>10%.

28. Uncontrolled blood pressure (defined as systolic >160 mmHg or diastolic >95 mmHg while subject was sitting)

29. History of either cerebral vascular accident and/or myocardial infarction within 180 days prior to Day 1

30. Renal failure requiring dialysis or renal transplant

31. History of other disease, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug, might affect interpretation of the results of the study, or rendered the subject at high risk for treatment complications

32. Pregnant or breast-feeding women

33. Sexually active men or women of childbearing potential who were unwilling to practice adequate contraception during the study were excluded (adequate contraceptive measures include stable use of oral contraceptives or other prescription pharmaceutical contraceptives for 2 or more menstrual cycles prior to screening; intrauterine device [IUD]; bilateral tubal ligation; vasectomy; condom plus contraceptive sponge, foam, or jelly or diaphragm plus contraceptive sponge, foam, or jelly).

34. Allergy to fluorescein

35. Participation in an investigational study within 30 days prior to screening visit that involved treatment with any drug (excluding vitamins and minerals) or device