Associations of serum lipid profiles with diabetic macular edema and retinal structural alterations

To explore the associations between serum lipid profiles and the presence of diabetic macular edema (DME), as well as its relationship with retinal structural alterations in patients with DME. This retrospective study was based on electronic health records. We identified 95 patients with type 2 diabetes (T2D), diabetic retinopathy (DR), and diabetic macular edema (DME), and used propensity score matching to select 190 patients with T2D and DR but without DME as controls. Clinical variables, lipid profiles, glycemic indicators, inflammatory markers, and renal function indicators were extracted. Renal function was assessed using blood urea nitrogen (BUN), serum creatinine, and estimated glomerular filtration rate (eGFR), which was calculated using the 2021 CKD-EPI creatinine equation. OCT-defined retinal structural alterations, including disorganization of retinal inner layers (DRIL), subretinal fluid (SRF), macular cyst, and EZ/ELM disruption, were evaluated by two experienced ophthalmologists. Logistic regression models were used to examine the associations between individual lipid indicators and DME or retinal structural alterations. Each lipid indicator was analyzed in a separate model to avoid multicollinearity. Restricted cubic spline (RCS) analyses were performed to explore the associations of TG and TyG index with DRIL. After propensity score matching, 95 patients with DME and 190 patients without DME were included. Compared with the nDME group, patients with DME had higher TG, HDL-C, LDL-C, TC, TyG index, and indirect bilirubin levels, and lower direct bilirubin levels. Continuous eGFR and the proportion of eGFR < 60 mL/min/1.73 m² did not differ significantly between groups. In separate logistic regression models additionally adjusted for eGFR, TG remained significantly associated with the presence of DME (OR = 2.34, 95% CI: 1.62–3.37, p < 0.001). TyG index was also associated with DME after eGFR adjustment (OR = 2.05, 95% CI: 1.37–3.06, p < 0.001). Among patients with DME, TG and TyG index were associated with DRIL after adjustment for clinical covariates and eGFR (TG: OR = 3.25, 95% CI: 1.59–6.65, p = 0.001; TyG index: OR = 3.93, 95% CI: 1.70–9.08, p = 0.001). Higher serum TG levels and TyG index were associated with the presence of DME and DRIL in multivariable-adjusted analyses. These findings suggest that lipid-related metabolic indicators may be linked to DME-related retinal structural alterations, although prospective studies are needed to validate these associations and clarify their clinical significance.