Longitudinal Association of Decreased Serum Uric Acid Level with the Thinning of Ganglion Cell Inner Plexiform Layer Thickness in Chinese Adults with Type 2 Diabetes Mellitus without Retinopathy

To explore the associations between serum uric acid (SUA) level change and changes in the retinal neurodegenerative biomarkers in type 2 diabetes mellitus patients without retinopathy. This is a prospective observational cohort study based on the baseline and 1-year follow-up data of the Guangzhou Diabetic Eye Study. Type 2 diabetes mellitus patients without retinopathy were recruited. Thicknesses of ganglion cell inner plexiform layer (GC-IPL) and peripapillary retinal nerve fiber layer (pRNFL) were measured via swept-source optical coherence tomography. The associations between SUA level change and the thinning rates of GC-IPL and pRNFL were analyzed using multivariate linear regression analysis. Sub-group analysis based on sex was constructed. A total of 1084 participants were enrolled in our study. After adjustment, both male and female patients with decreased SUA levels in higher baseline SUA level group had a significantly slower thinning rate of GC-IPL than those with non-decreased SUA levels. In higher baseline SUA level with decreased SUA level group, male patients exhibited significantly slower thinning rate of inferior GC-IPL, while female patients exhibited significantly slower thinning rate of inferior and nasal GC-IPL and inferior pRNFL, when compared to those with non-decreased SUA levels. Our findings prove that decreased SUA level is associated with a slower GC-IPL thinning rate in higher baseline SUA level group, suggesting that decreased SUA level could be constituted as a potential future control target to delay the neurodegeneration in type 2 diabetes mellitus patients.