Elevated serum lipoprotein(a) levels as a potential risk factor for diabetic retinopathy in type 2 diabetes: a meta-analysis.

Purpose: This meta-analysis aimed to clarify the correlation between serum lipoprotein(a) [Lp(a)] levels and diabetic retinopathy (DR) in type 2 diabetes (T2D) individuals.

Methods: We searched electronic databases, including PubMed, Web of Science, and Embase, for relevant observational studies evaluating the association between serum Lp(a) levels and the risk of DR. Odds ratios (ORs) with 95% confidence intervals (CIs) were summarized to indicate the association between a high Lp(a) and the risk of DR. Data were extracted and pooled using a random-effects model to account for variability among studies. Heterogeneity was assessed using the I² statistic, and publication bias was evaluated through funnel plots and Egger's test.

Results: Eleven observational studies were included. Compared to T2D patients of the lowest Lp(a) category, those of the highest Lp(a) category were associated with a higher risk of DR (OR: 2.05, 95% CI: 1.43-2.93, I² = 83%, p < 0.001). Subgroup analyses suggested this association was predominantly observed in cross-sectional and case-control studies but not cohort studies (p for subgroup differences = 0.03). Additionally, the link between Lp(a) and DR was consistent across variables such as study country, Lp(a) cutoff values, analysis model (univariate or multivariate), and adjustment for concurrent medication use. A further meta-analysis suggested a significant relationship between elevated Lp(a) levels and proliferative DR (OR: 1.90, 95% CI: 1.03-3.48, I² = 86%, p = 0.04).

Conclusion: Elevated serum Lp(a) levels are associated with an increased risk of DR in individuals with T2D.