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Glycemic Velocity and Early Retinal Microvascular Change With GLP-1RA Versus SGLT2i Initiation in Type 2 Diabetes (GLIDE)

NCT07723820

Not Yet RecruitingN/A

Sponsor: Thammasart University Hospital

Conditions: Type 2 Diabetes Mellitus, Diabetic Retinopathy (DR)

Interventions: GLP-1 Receptor Agonists, SGLT2 inhibitor

Countries: Thailand

The GLIDE study looks at how the small blood vessels of the eye respond during the first months of a new diabetes medicine. Two widely used classes of glucose-lowering drugs, GLP-1 receptor agonists and SGLT2 inhibitors, are compared in adults with type 2 diabetes who have no diabetic retinopathy or only early (mild) diabetic retinopathy. When blood sugar (HbA1c) falls quickly after starting treatment, the retina can undergo a brief, temporary worsening before it stabilizes and benefits over the long term. This study asks whether it is the speed of that blood-sugar reduction, which we call "glycemic velocity," rather than the specific drug, that drives early changes in retinal and choroidal blood flow. Participants are patients whose own physician has decided, independently of the study, to start one of these two drugs for the first time. The study does not choose, provide, or change any medicine; it adds only eye imaging, blood tests, and observation. Each participant is followed with specialized, non-invasive eye scans, optical coherence tomography angiography (OCT-A) and structural/choroidal OCT, together with HbA1c and other measurements, at the start of treatment and again over the following months. The main measurement is the change, from the start of treatment to month 3, in the density of the tiny deep-layer capillaries at the center of the retina, measured on OCT-A. The study will test whether faster HbA1c reduction is linked to greater early change in these vessels and, using statistical mediation analysis, will estimate how much of any difference between the two drug groups is explained by glycemic velocity versus a direct drug effect. If glycemic velocity, a factor physicians can influence by adjusting how quickly treatment is intensified, turns out to drive early retinal change, the findings could guide safer treatment strategies and help identify patients who need closer eye monitoring when starting these medicines.

Eligibility overview

Sex: ALL

Age: 18 Years to —

Healthy volunteers: No

Study type: OBSERVATIONAL

Eligibility criteria

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.

Locations (1)

Pathum Thani, Khlong Luang, Thailand