Glycemic Velocity as a Modifiable Determinant of Early Retinal Microvascular and Choroidal Change During Initiation of GLP-1 Receptor Agonist Versus SGLT2 Inhibitor Therapy in Type 2 Diabetes: A Prospective Multimodal Retinal Imaging Cohort Study (the GLIDE Study)
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 入组人数
- 126
- 试验地点
- 1
- 主要终点
- Change in parafoveal deep-capillary-plexus (DCP) vessel density on OCT angiography
研究概览
简要总结
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.
详细描述
Background and rationale:
GLP-1 receptor agonists (GLP-1RAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) are central therapies for type 2 diabetes, and their ocular safety remains unresolved. The cardiovascular outcome trial SUSTAIN-6 reported more adjudicated diabetic-retinopathy complications with semaglutide than placebo, concentrated among patients with pre-existing retinopathy and concurrent insulin use, whereas large real-world datasets have not reproduced a consistent signal. Mechanistic and meta-analytic work increasingly attributes the trial signal not to the molecule itself but to the magnitude and rapidity of the accompanying fall in glycated hemoglobin (HbA1c), the long-recognized phenomenon of transient "early worsening" of retinopathy after rapid glycemic correction, first characterized in the Oslo study and subsequently in the DCCT.
Central hypothesis and definition of the exposure:
The study formalizes the driver of early worsening as a continuous, patient-level exposure termed glycemic velocity: the rate at which HbA1c falls after treatment initiation, computed as (HbA1c at baseline - HbA1c at Month 3) divided by elapsed time and expressed in percentage points per month. It is analyzed per +1 SD, with a clinically anchored secondary scale of +0.5 percentage points per month and a pre-specified test for non-linearity or a threshold effect. Baseline HbA1c and the absolute magnitude of HbA1c reduction are retained as separate covariates so that the effect of rate is distinguished from that of magnitude and of starting level. The complementary mechanistic hypothesis is that a transient disturbance of retinal and choroidal perfusion (relative hypoxia) is the shared intermediate underlying GLP-1RA-associated ocular signals, and that its magnitude tracks with glycemic velocity.
Rationale for the design:
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Prospective
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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.
排除标准
- •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.
研究组 & 干预措施
SGLT2 inhibitor initiators
Adults with type 2 diabetes and no-to-mild NPDR who are starting a first-ever SGLT2 inhibitor, prescribed by the treating physician independently of the study. Active comparator that shares the glucose-lowering indication but is not classically associated with early retinopathy worsening. Followed with the identical battery.
干预措施: SGLT2 inhibitor (Drug)
GLP-1 receptor agonist initiators
Adults with type 2 diabetes and no-to-mild NPDR who are starting a first-ever GLP-1 receptor agonist, prescribed by the treating physician independently of the study. Followed with the standardized multimodal retinal-imaging and metabolic battery. Primary exposure of interest, glycemic velocity, is measured within this cohort.
干预措施: GLP-1 Receptor Agonists (Drug)
结局指标
主要结局
Change in parafoveal deep-capillary-plexus (DCP) vessel density on OCT angiography
时间窗: Baseline to Month 3
Vessel density (%) of the deep capillary plexus in the parafoveal ring on OCT angiography (fixed macular scan, validated quantification, pre-specified image-quality threshold, masked grading); primary metric is the change from baseline to Month 3.
次要结局
- Best-corrected visual acuity (BCVA)(Baseline to Month 3)
- Superficial capillary plexus (SCP) vessel density and perfusion density(Baseline to Month 3)
- Foveal avascular zone (FAZ) area(Baseline to Month 3)
- Subfoveal choroidal thickness(Baseline to Month 3)
- Choroidal vascularity index (CVI)(Baseline to Month 3)
- Central subfield thickness(Baseline to Month 3)
- Proportion of drug-class effect mediated by glycemic velocity(Baseline to Month 3)
- Diabetic-retinopathy severity step-change (ETDRS)(Baseline to Month 3)
研究者
Wit Tharanon
Research fellow in Ophthalmology, Faculty of medicine, Thammasat University
Thammasat University Hospital