Purpose: To identify optical coherence tomography (OCT) patterns of diabetic macular edema (DME) predictive of visual outcomes after intravitreal bevacizumab (IVB; Avastin®) injection. Methods: We retrospectively examined 56 consecutive eyes that were given IVB injections for DME alongside the preoperative macular OCT data. Using this information, we categorized the eyes into 2 groups: group 1 showing diffuse patterns; group 2 demonstrating cystoid macular edema (CME). Result: The mean follow-up period was 11.66 ± 3.98 months. Group 1 eyes gained 0.04 ± 9.27 ETDRS letters (p = 0.984), while group 2 eyes gained 5.79 ± 9.98 ETDRS letters (p = 0.005). Mean macular thickness decreased by 72.79 ± 145.74 µm in group 1 (p = 0.014) and by 223.71 ± 224.52 µm in group 2 (p< 0.001). Conclusion: Patients showing CME upon OCT achieved greater improvements in visual acuity and macular thickness after IVB injection than patients with diffuse macular edema. The type of macular edema shown by OCT may provide an objective guideline in predicting the response of DME to IVB injection.