The gut-retina axis: association of dietary index for gut microbiota with diabetic retinopathy in diabetic patients-a cross-sectional study from NHANES 2009-2018.

BACKGROUND

The gut-retina axis, an emerging area of research, has uncovered the bidirectional link between the intestines and retina, offering new insights into ophthalmic disease management. Diabetic retinopathy (DR), a common diabetes complication with a digestive-related connection, lacks large-sample retrospective studies on the impact of gut microbiota-related diets. The association between the Dietary Index for Gut Microbiota (DI-GM) and DR requires further investigation.

METHODS

1,285 diabetic patients from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2009 to 2018 were analyzed. DI-GM, based on 14 foods or nutrients intake, served as the exposure variable. Associations were assessed via Spearman correlation, weighted logistic regression, restricted cubic spline (RCS) analysis, and subgroup analyses.

RESULTS

Spearman analysis revealed predominantly inverse correlations among DI-GM components. After adjusting for confounders, each 1-point increase in DI-GM was associated with a 12% lower DR risk (OR = 0.88, 95% CI 0.78-0.99, P = 0.039). The Q4 DI-GM exhibited a 67% reduced DR risk compared to Q1 (OR = 0.33, 95%CI 0.12-0.88, P = 0.028). RCS analysis identified a nonlinear dose-response relationship (P-nonlinearity < 0.01), with rapid risk reduction at DI-GM < 4 and diminishing returns thereafter. Subgroup analyses indicated that most subgroup associations showed no statistically significant differences (interaction P > 0.05), except for participants with long-standing diabetes, without hypertension and BMI < 25 (OR = 0.55, 95%CI: 0.33-0.93, P = 0.03).

CONCLUSIONS

Higher DI-GM scores are linked to lower DR risk, supporting dietary optimization (e.g., increased whole grains/vegetables, reduced processed meat) as a potential strategy for DR prevention through gut microbiota modulation. These findings advance gut-retina axis theory and provide actionable dietary guidelines for diabetes complications.