Could the speed of blood sugar drop harm the eyes? a study puts it to the test.

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults aged 18 years or older with a documented diagnosis of type 2 diabetes mellitus. * Clinical decision, made by the treating physician independently of the study, to initiate a first-ever GLP-1 receptor agonist or a first-ever SGLT2 inhibitor. * Baseline retinal status ranging from no diabetic retinopathy to mild non-proliferative diabetic retinopathy (NPDR) in the study eye(s), confirmed by fundus photography / ETDRS grading. * Baseline HbA1c within a range permitting a measurable subsequent change (e.g., 7.0% or higher), obtained within 30 days before or after the scheduled ophthalmic assessment. * Media sufficiently clear and fixation adequate to obtain gradable OCT-A and OCT images. * Able and willing to provide written informed consent and to attend scheduled follow-up visits. Exclusion Criteria: * Moderate-to-severe NPDR, proliferative diabetic retinopathy, or center-involving diabetic macular edema at baseline. * Prior or concurrent treatment for diabetic retinopathy or maculopathy: pan-retinal or focal/grid laser photocoagulation, intravitreal anti-VEGF or corticosteroid therapy, or vitreoretinal surgery. * Any prior exposure to a GLP-1 receptor agonist or SGLT2 inhibitor (to preserve the new-user design). * Type 1 diabetes, latent autoimmune diabetes of adults, or secondary diabetes. * Other retinal or choroidal disease that would confound microvascular/choroidal measurement: age-related macular degeneration, retinal vein or artery occlusion, uveitis, high myopia (spherical equivalent more negative than -6.0 D or axial length greater than 26.0 mm), or significant media opacity precluding imaging. * Coexisting glaucoma or optic neuropathy that independently alters retinal vascular or neural metrics. * Recent (within 3 months) intraocular surgery in the study eye, including cataract surgery. * Uncontrolled systemic hypertension or a known systemic condition (e.g., significant anemia, severe renal impairment with eGFR \< 30 mL/min/1.73 m², or active malignancy) that independently affects retinal perfusion or oximetry, at investigator discretion. * Pregnancy, or planned simultaneous initiation of insulin such that the index glucose-lowering exposure cannot be attributed (concurrent stable insulin is permitted and recorded as a pre-specified effect modifier). * Inability to provide informed consent or to comply with the imaging and follow-up schedule.