Gestational Diabetes Mellitus is associated with reduced superficial capillary plexus vessel density and retinal thinningEye Scans Reveal Early Changes in Blood Vessels for Pregnant Women with Diabetes

PURPOSE: Gestational diabetes mellitus (GDM) may induce subtle retinal microvascular alterations even in the absence of clinical diabetic retinopathy. This study represents the first systematic review and meta-analysis to comprehensively evaluate retinal and choroidal structural and microvascular alterations in women with GDM. METHODS: A systematic search of PubMed, Embase, Scopus, and Web of Science up to September 2025 identified cross-sectional studies comparing OCT or OCTA parameters between women with GDM and healthy pregnant (HP) or healthy non-pregnant (HNP) controls. Pooled standardized mean differences (SMDs) were calculated using random-effects models with Knapp-Hartung adjustment. RESULTS: Twelve studies encompassing 2,798 eyes from 1,997 women were included. Compared with HP controls, eyes with GDM exhibited a small but statistically significant reduction in mean and parafoveal superficial capillary plexus vessel density (SMD = -0.07 and - 0.13, respectively; both p < 0.05) and thinning of the inferior peripapillary retinal nerve fiber layer (SMD = -0.25; p = 0.003), all with zero heterogeneity (I² = 0%). No significant differences were observed in central macular thickness, foveal avascular zone area, deep plexus density, or subfoveal choroidal thickness. CONCLUSIONS: This systematic synthesis demonstrates that GDM is associated with early, subclinical neurovascular alterations, particularly reduced superficial capillary density and inferior retinal nerve fiber layer thinning, while overall retinal and choroidal structures remain preserved. These findings introduce OCTA as a potential sensitive biomarker for detecting early microvascular compromise in GDM and emphasize the need for longitudinal studies to determine their reversibility postpartum.