Reduced Aqueous Humor TGF-β2 Levels in Diabetic Cataract: A Comparative Analysis with NF-κB

Background/Objectives: Type 2 diabetes may impair anterior segment immune regulation. Because transforming growth factor-β2 maintains ocular immune privilege, while nuclear factor-κB is linked to inflammatory activation, we compared their aqueous humor levels in cataract patients with and without diabetes. Methods: In this prospective cross-sectional study, aqueous humor samples were collected from 90 patients (30 diabetic, 60 non-diabetic) via anterior chamber needle aspiration at the commencement of routine phacoemulsification, prior to viscoelastic injection, without additional intervention. Transforming growth factor-β2 and nuclear factor-κB levels were then measured using enzyme-linked immunosorbent assay (ELISA). Between-group comparisons and ROC curve analyses were performed to evaluate differences in biomarker levels and their discriminative ability in distinguishing diabetic status. Covariate-adjusted analysis (ANCOVA) was additionally performed. Results: Transforming growth factor-β2 levels were significantly lower in the diabetic group (p < 0.001), while nuclear factor-κB levels showed no significant difference (p = 0.285). The between-group difference in transforming growth factor-β2 remained significant after adjustment for cataract grade and hypertension duration (F(1,86) = 17.901, p < 0.001, partial η2 = 0.172; Cohen’s d = 0.94). Transforming growth factor-β2 demonstrated high specificity (100%) but limited sensitivity (45%) for identifying diabetic status at a cut-off of <449.25 ng/L; however, given the small sample size and exploratory nature of the study, this specificity value should be interpreted with caution and requires validation in larger cohorts. Conclusions: Lower aqueous humor TGF-β2 levels in diabetic cataract patients, independent of cataract severity and hypertension duration, suggest that TGF-β2 suppression may represent an earlier molecular event in anterior segment immune dysregulation preceding overt inflammatory activation. While TGF-β2 shows exploratory biomarker potential, validation in larger, prospective, mechanistic studies is required before clinical application.