Glycemic Control, Animal Protein Intake, and the Risk of Diabetic Retinopathy Progression Among Patients With Type 2 Diabetes

Effective glycemic control and food consumption play crucial roles in modulating diabetic retinopathy (DR) progression. This observational longitudinal study explored the hemoglobin A1c (HbA1c) and dietary patterns and their associations with the risk and progression of DR among 369 individuals with type 2 diabetes. Participants were grouped by DR development as DM (no DR, n = 280), DR-M (stable DR, n = 40), and DR-W (worsening DR, n = 49) over 3 years using the American Academy of Ophthalmology DR Severity Scale. Dietary intake was evaluated using a validated food frequency questionnaire and principal component analysis. High intake was defined as a component score ≥ 2/3 and low as < 2/3. Over 3 years, HbA1c ≥ 7% and a diabetes duration > 20 years linked to a higher risk of DR-M, with stronger effects seen with high animal protein intake. High animal protein intake was independently correlated with DR-W (OR = 2.58, 95% CI: 1.17-5.70). A one-unit increase in HbA1c and HbA1c ≥ 7% resulted in 2.33-fold (95% CI: 1.08-5.06) and 8.25-fold (95% CI: 1.64-41.43) higher risks of DR-W, respectively, in those with high, but not low intake. Poor glycemic control and diabetes duration exceeding 20 years served as key contributors to DR-M development and persistence over 3 years, with higher risks in strata of high animal protein intake. High animal protein intake also intensified the adverse impact of poor glycemic control on DR-W. In summary, moderating animal protein consumption, alongside optimal glycemic management, may be relevant to DR progression. Given small DR subgroup sizes, these exploratory findings require confirmation in larger, independent cohorts.