The purpose of the study is to evaluate the efficacy and safety of as-needed dexamethasone (DEX) retreatment compared with standard DEX retreatment combined with PRN ranibizumab injections among patients with persistent diabetic macular edema (DME). Twenty-eight patients with persistent macular edema having recurrence earlier than 6 months after initial DEX implantation were included in this retrospective study. Group I consisted of 13 patients retreated using monthly PRN ranibizumab injections combined with standard 6-monthly DEX implantation; Group II consisted of 15 patients retreated with DEX implantation earlier than 6 months on an "as-needed" basis. There was no significant difference between the groups with regarding to age, gender, HbA1C levels, duration of diabetes, duration of macular edema, baseline central macular thickness (CMT), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) values (p > 0.05). The mean follow-up time of the whole study population was 10.13 ± 1.75 months (range 9-15). The mean CMT values were significantly decreased in both groups compared to baseline values except for the 6th-month CMT in Group I (p < 0.05). The mean logMAR BCVA values were not statistically different between groups during the follow-up compared to baseline BCVA values (p > 0.05). However, a significant change in mean BCVA from baseline was seen at 4th, 6th, and 9th months in Group II (p ≤ 0.05). The mean number of total intravitreal treatments was 3.50 ± 0.77 in Group I and 2.53 ± 0.51 in Group II (p = 0.001). During the follow-up period, one patient in Group I and five patients in Group II had increased IOP (≥25 mmHg). Early DEX retreatment improved vision with superior anatomical improvement at 6th month and with fewer intravitreal treatments in eyes with DME. However, improvement in visual acuity is similar with standard DEX retreatment combined with PRN ranibizumab group.