Lymphocyte–to–high–density lipoprotein ratio is negatively associated with diabetic macular edema in type 2 diabetic patients

Background Systemic immune-inflammatory imbalance plays a potential role in the development of diabetic macular edema (DME). The lymphocyte-to-high-density lipoprotein ratio (LHR) can reflect the systemic immune-inflammatory status. This study aimed to explore the relationship between LHR and DME. Methods This retrospective study enrolled 423 patients with diabetic retinopathy admitted to the same hospital between January 2022 and December 2024. Patients were categorized into DME (n = 163) and non-DME groups (n = 260) based on optical coherence tomography. Clinical and laboratory information was gathered, and LHR was calculated. Logistic regression models were conducted to explore the association between LHR and DME. Quartile grouping, quartile-based trend test, and subgroup analyses were used to verify the pattern of association. Restricted cubic splines (RCS) were used to assess nonlinear relationships. Sensitivity analysis was also conducted. Results The DME group exhibited a significantly lower LHR level than in the non-DME group [1.55 (1.19, 2.04) vs. 1.94 (1.38, 2.47), P < 0.001]. Further adjusted regression models revealed that reduced LHR independently correlated with DME (aOR = 0.714, 95% CI: 0.541–0.942, P = 0.017). Quartile analysis demonstrated that the DME incidence in the Q1 group (LHR ≤ 1.32) was 48.1%, markedly higher than 27.6% in the Q4 group (LHR ≥ 2.40) (P = 0.002). RCS analysis verified a negative linear correlation between LHR and the odds of DME (P overall = 0.039, P nonlinear = 0.178). Sensitivity analysis supported the association (aOR = 0.698, 95% CI: 0.511–0.952, P = 0.023). Conclusion Low LHR is independently associated with the presence of DME.