Intravitreal bevacizumab (IVB), often injected during cataract surgery, is currently the main treatment for diabetic macular edema. This retrospective study aimed to compare the effectiveness of IVB injections alone and during cataract surgery in patients with diabetic macular edema. We examined 43 eyes in 40 patients who underwent cataract surgery with simultaneous IVB injections 3–12 months after IVB injections alone. Best-corrected visual acuity and central subfield macular thickness (CMT) were measured 1-month post-injection. The CMTs of the same eyes with IVB-only first and combined-treatment procedures later were 384 ± 149 vs. 315 ± 109 μm pretreatment (p= 0.0002), and after 1 month, they were 319 ± 102 vs. 419 ± 183 μm (p< 0.0001). In the IVB-only procedure, 56.1% of eyes had CMT < 300 μm 1 month after the injection compared to 32.5% after the combined treatment. Therefore, on average, when IVB was administered during cataract surgery, CMT increased, whereas after IVB injection alone, it effectively decreased. More prospective trials with large sample sizes are needed to evaluate the effectiveness of IVB injection performed simultaneously with cataract surgery.