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Association between HbA1c level and retinal nerve fiber layer thickness in non-proliferative diabetic retinopathy
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Abstract
Objective: To investigate the association between Hemoglobin A1c (HbA1c) and retinal nerve fiber layer (RNFL) thickness in patients with type 2 diabetes mellitus (DM) at the non-proliferative diabetic retinopathy stage, considering that retinal neurodegeneration is an early event in diabetic retinopathy (DR). Methods: This cross-sectional study included 50 patients with type 2 DM, categorized into without diabetic retinopathy (NDR, n=30) and non-proliferative diabetic retinopathy (NPDR, n=20) groups. Peripapillary RNFL thickness was measured using spectral-domain optical coherence tomography (SD-OCT). Systemic data, including HbA1c, blood pressure, BMI, and DM duration, were collected and analyzed for correlations. Results: The NPDR group exhibited a significantly longer DM duration, higher systolic blood pressure, and elevated HbA1c levels compared to the NDR group (p<0.05). Average RNFL thickness was significantly lower in the NPDR group for both the right (94.3 ± 5.53 µm vs. 100.77 ± 5.26 µm, p<0.001) and left eyes (95.0 ± 5.38 µm vs. 100.27 ± 6.65 µm, p=0.005). A significant negative correlation was found between average RNFL thickness and HbA1c levels, duration of DM, and systolic blood pressure. Conclusion: RNFL thinning is a significant structural change in early DR, strongly associated with poor glycemic control, longer disease duration, and elevated systolic blood pressure. These findings highlight the potential of RNFL thickness as a biomarker for early neurodegeneration and emphasize the importance of managing systemic risk factors.
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Keywords
Diabetic Retinopathy, Retinal Nerve Fiber Layer, HbA1c, Neurodegeneration, Optical Coherence Tomography, Type 2 Diabetes.
References
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