Purpose: To report the vision-related quality of life in patients with diabetic macular edema (DME) in a population-based study. Methods: In this cross-sectional study, we analyzed 1,659 subjects with type 2 diabetes. Questionnaires were administered to assess the patient's vision-related quality of life. Diabetic macular edema severity was graded according to the established protocols. A subject's DME score ranged from 1 (no DME in either eye) to 7 (severe bilateral DME) using predefined criteria. Results: Composite 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) scores for participants with DME were 88.9 (interquartile range [IQR]: 76.2-94.9) compared with 92.0 (IQR: 82.7-96.0) for those without DME (P < 0.001). Locally weighted scatterplot smoothing plots depicted a consistent decline in composite NEI-VFQ-25 scores corresponding to the escalation of bilateral DME severity: starting from 88.59 for no DME in either eye, progressing through 86.65, 85.83, 85.31, 84.91, 83.85, and culminating at 82.71 for bilateral severe DME. Notably, the locally weighted scatterplot smoothing plots highlighted significant NEI-VFQ-25 composite score reduction at unilateral mild DME (slope m = -1.94). Conclusion: Significant changes in vision-related quality of life manifest in the early stage of DME. Therefore, early identification and intervention for these patients are crucial clinical objectives.