Efficacy and Safety of RC28-E Versus Aflibercept in Diabetic Macular Edema

Inclusion Criteria: * Documented diagnosed with type I or type II diabetes mellitus. * Hemoglobin A1c (HBA1c) of less than or equal to (≤) 10% within 2 months prior to Day 1. * Ability and willingness to undertake all scheduled visits and assessments. * The study eye must meet the following requirements: * macular thickening secondary to diabetic macular edema (DME) involving the center of the fovea. * decreased visual acuity attributable primarily to DME, the best corrected visual acuity (BCVA) 19 or more letters, 78 letters or less. Exclusion Criteria: * The study eye with high risk of proliferative diabetic retinopathy. * The macular edema of the study eye is mainly caused by other diseases or factors other than DME. * Treatment with panretinal photocoagulation or macular laser within 3 months prior to Day 1 to the study eye. * Administration of IVT any other anti-VEGF drugs in the study eye within 3 months and/or in the other eye within 7 days prior to Day 1. * Any intraocular long-acting or sustained release corticosteroid treatment (e.g., dexamethasone intravitreal implant) in the study eye within 6 months prior to Day 1. * Active intraocular or periocular infection or active intraocular inflammation in either eye. * The study eye with poorly controlled glaucoma. * A history of idiopathic or autoimmune related uveitis in either eye. * History of stroke (cerebrovascular accident) or myocardial infarction within 6 months prior to Day 1. * Uncontrolled blood pressure, defined as a systolic value greater than (\>)180 millimeters of mercury (mmHg) and/or a diastolic value \>100 mmHg while a patient is at rest. * Currently pregnant or breastfeeding, or intend to become pregnant during the study. * Any current or history of ocular disease other than DME that may confound assessment of the macula or affect central vision in the study eye. * Any current ocular condition which, in the opinion of the investigator, is currently causing or could be expected to contribute to irreversible vision loss due to a cause other than DME in the study eye. * Other protocol-specified inclusion/exclusion criteria may apply.