Remote Ischemic Conditioning for Non-Proliferative Diabetic Retinopathy

Inclusion Criteria: * Age between 40 and 80 years. * Diagnosed with Type 2 diabetes mellitus. * Diagnosed with mild to moderate non-proliferative diabetic retinopathy (NPDR) with a DR Severity Score (DRSS) grade of 20-47D. * Capable of performing daily activities independently. * Willing and able to provide informed consent. Exclusion Criteria: * Presence of diabetic macular edema (macular thickness \> 250 μm). * Significant eye diseases affecting evaluation, such as high myopia, severe cataract, corneal leucoma, glaucoma, retinal detachment, retinal vein occlusion, congenital eye diseases, ocular tumors, or severe infection. * History of ocular laser or intraocular surgery. * Poor imaging quality due to refractive media opacity. * Contraindication to fluorescein fundus angiography. * Unstable blood glucose (HbA1c ≥ 8.0%) despite oral antidiabetic drugs. * Severe diabetes complications within the past 6 months. * Severe, sustained hypertension (systolic ≥ 180 mmHg or diastolic ≥ 110 mmHg). * Body mass index (BMI) ≥ 28 kg/m². * Hepatic or renal insufficiency: Alanine aminotransferase or aspartate aminotransferase \> 2 times the upper limit of normal. Estimated glomerular filtration rate (eGFR) \< 60 mL/min/1.73m². Urine albumin/creatinine ratio ≥ 30 mg/g. * Myocardial infarction within the past 6 months. * Neurological diseases such as Alzheimer's, Parkinson's, cerebrovascular disease, intracranial tumor, cerebrovascular malformation, or aneurysm. * Contraindications to RIC, including one-sided subclavian artery stenosis, upper limb injuries or vascular diseases, or limb deformities. * Severe systemic diseases, such as malignant tumors with a life expectancy of less than 24 months. * Known pregnancy or breastfeeding. * Participation in other experimental clinical studies. * Any other conditions deemed unsuitable by the investigator.