Association of Serum Meteorin-Like with OCTA Metrics in Type 2 Diabetic Nonproliferative Retinopathy: A Cross-Sectional Study.

PURPOSE: Meteorin-like (Metrnl), a novel secreted myokine, has been implicated in metabolic imbalance and the pathogenesis of type 2 diabetes mellitus (T2DM). The present work sought to determine whether circulating Metrnl concentrations are associated with alterations in retinal microcirculation, assessed via optical coherence tomography angiography (OCTA), in individuals living with T2DM. PATIENTS AND METHODS: This cross-sectional investigation enrolled 160 adults with T2DM, including those with and without nonproliferative diabetic retinopathy (NPDR). Each participant underwent OCTA imaging, from which vessel density (VD), foveal avascular zone (FAZ) area, and ganglion cell complex (GCC) thickness were automatically extracted. Multivariable analytical models were constructed to evaluate independent associations between serum Metrnl levels and OCTA-derived microvascular metrics. RESULTS: Totally, 160 eyes from 160 patients (median age: 56 years [IQR 48-64]; 64% male; median diabetes duration: 10 years [IQR 5-16]) were analyzed. Serum Metrnl concentrations were markedly reduced in DR patients relative to those without DR (425.59 ± 95.69 vs 479.02 ± 96.85 pg/mL, p = 0.002). Decreasing Metrnl concentrations were accompanied by a reduction in retinal VD. After adjustment for potential confounders, higher Metrnl levels remained significantly associated with greater VD in both the superficial vascular complex and deep vascular complex. No significant relationships were observed between Metrnl levels and FAZ area or GCC thickness. CONCLUSION: Serum Metrnl concentrations are positively associated with retinal microvascular perfusion in T2DM. Further studies are needed to explore whether Metrnl plays a role in the development or progression of DR.