Glycemic Control and Retinal Microvascular Changes

Study Overview
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Brief Summary
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The goal of this prospective, observational study is to compare in the association of glycemic control and retinal microvascular changes in patients with type 2 diabetes mellitus (T2DM) without diabetic retinopathy (DR). The main question it aims to answer are: • Do degenerative changes in retinal microvasculature or nerves depend on glycemic control even before diabetic retinopathy is detected? Participants will receive an annual routine comprehensive examination including ultra-widefield fundus photography, spectral domain optical coherence tomography (OCT), and swept-source optical coherence tomography angiography (OCTA).

Official Title
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Glycemic Control and Retinal Microvascular Changes in Type 2 Diabetes Mellitus Patients Without Clinical Retinopathy

Conditions
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Diabetic Retinopathy, Neurodegeneration, Blood Sugar; High

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: The study included 30-70-year-old patients with T2DM without known DR at baseline who underwent regular screening for DR at the department of ophthalmology. Who underwent regular checkups for DR between January 2019 and August 2022 at Dongguk University Ilsan Hospital. The controls included patients without DM who presented for regular ophthalmic examination. Exclusion Criteria: patients with a history of retinal or choroidal diseases (i.e., age-related macular degeneration, retinal vein occlusion, uveitis, retinal detachment, and central serous chorioretinopathy), glaucoma, or optic neuropathy patients with neurodegenerative diseases, such as Parkinson's disease and dementia.

Ages Eligible for Study
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Minimum Age: 30 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Healthy control<br>The controls included patients without DM who presented for regular ophthalmic examination. | |
| intensive control (IC) group<br>The mean HbA1c level was calculated during the 12 months prior to the OCT and OCTA. Based on the mean HbA1c level, T2DM patients were divided into intensive control (IC; mean HbA1c ≤ 7.0%) and moderate control (MC; mean HbA1c > 7.0%) groups | |
| moderate control (MC) group<br>The mean HbA1c level was calculated during the 12 months prior to the OCT and OCTA. Based on the mean HbA1c level, T2DM patients were divided into intensive control (IC; mean HbA1c ≤ 7.0%) and moderate control (MC; mean HbA1c > 7.0%) groups | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The foveal avascular zone (FAZ) area (mm^2) | FAZ was defined as the avascular area in the foveal center. | Upon initial registration and through study completion, an average of 1 year | 
| central foveal retinal thickness (um) and macular ganglion cell-inner plexiform layer (GC-IPL) thickness (um) | Retinal layer thickness were calculated automatically using the bundled software | Upon initial registration and through study completion, an average of 1 year | 
| Retinal vessel density (VD, %) | The VD (%) was calculated using the following formula: VD (%) = vascular area (pixel) / (total area - FAZ area) (pixel) × 100. | Upon initial registration and through study completion, an average of 1 year |