INTRODUCTION: Anti-vascular endothelial growth factor (VEGF) therapy is the first-line treatment for diabetic macular edema (DME). We investigated the effect of initial glycosylated hemoglobin (HbA1c) level and glomerular filtration rate (GFR) on treatment outcomes in patients with DME receiving anti-VEGF injections in routine clinical practice. METHODS: A retrospective analysis of data from the prospective, multi-center, observational Fight Retinal Blindness! registry was performed. A total of 178 eyes with DME treated with anti-VEGF agents (ranibizumab or aflibercept) from 1 January 2010 to 31 March 2019 were enrolled in the analysis, with the long study period to allow for up to 24 months of follow-up. Data for eyes were tracked in the Fight Retinal Blindness! registry, and clinical parameters were collected by using local software. Changes in visual (best-corrected visual acuity [BCVA], in letters) and anatomic outcomes (central subfield thickness [CST], in microns) between subgroups of patients according to baseline HbA1c level (≤ 7% vs. > 7%) and GFR (> vs. ≤ 60 ml/min/m(2) at 24 months were assessed. RESULTS: The multivariate adjusted mean improvement in BCVA at 24 months of treatment was + 5.2 and + 6.8 letters in subgroups with baseline HbA1c level ≤ 7% and > 7%, respectively (p = 0.541), and + 6.9 and + 6.4 letters in subgroups with GFR > 60 and < 60 ml/min/1.73 m(2), respectively (p = 0.852). The multivariate adjusted mean CST reduction was - 89.9 and - 76.4 µm in subgroups with baseline HbA1c level ≤ 7% and > 7%, respectively (p = 0.505), and - 85 and - 115 µm in subgroups with baseline GFR > 60 and ≤ 60 ml/min/1.73 m(2), respectively (p = 0.130). CONCLUSION: These results seem to indicate that visual and anatomical improvement in patients receiving intravitreal VEGF inhibitors for DME are independent of baseline HbA1c level and GFR, leading to the conclusion that high HbA1c levels or low GFR should not dictate injection timing in routine clinical practice. This study offers valuable insights for ophthalmologists, enabling a personalized treatment approach and optimizing DME patient outcomes.