The Causal Relationship and Association between Biomarkers, Dietary Intake, and Diabetic Retinopathy: Insights from Mendelian Randomization and Cross-Sectional Study

BACKGRUOUND: Diabetic retinopathy (DR) is a major cause of vision loss, linked to hyperglycemia, oxidative stress, and inflammation. Despite advancements in DR treatments, approximately 40% of patients do not respond effectively, underscoring the need for novel, noninvasive biomarkers to predict DR risk and progression. This study investigates causal relationships between specific biomarkers, dietary factors, and DR development using Mendelian randomization (MR) and cross-sectional data. METHODS: We conducted a two-phase analysis combining MR and cross-sectional methods. First, MR analysis examined causal associations between 35 biomarkers, 226 dietary factors, and DR progression using data from the UK Biobank and Genome-Wide Association Study (GWAS) datasets. Second, a cross-sectional study with National Health and Nutrition Examination Survey (NHANES) and a clinical cohort from Tianjin Medical University Eye Hospital validated findings and explored biomarkers' predictive capabilities through a nomogram-based prediction model. RESULTS: MR analysis identified eight biomarkers (e.g., glycosylated hemoglobin [HbA1c], high-density lipoprotein cholesterol [HDL-C]) with significant causal links to DR. Inflammatory markers and metabolic factors, such as high glucose and HDL-C levels, were strongly associated with DR risk and progression. Specific dietary factors, like cheese intake, exhibited protective roles, while alcohol intake increased DR risk. Validation within NHANES and Tianjin cohorts supported these causal associations. CONCLUSION: This study elucidates causal relationships between biomarkers, dietary habits, and DR progression, emphasizing the potential for personalized dietary interventions to prevent or manage DR. Findings support the use of HDL-C, HbA1c, and dietary factors as biomarkers or therapeutics in DR, though further studies are needed for broader applicability.