Retinal imaging in gestational diabetes mellitus: systematic review

To examine the differences in retinal structure and vasculature between women with gestational diabetes mellitus (GDM) and normoglycemic pregnant controls.

This was a systematic review of the available literature on retinal assessment in pregnancies with GDM compared with non-GDM controls, conducted in PubMed, EMBASE via Ovid, The Cochrane Library and Scopus databases in November 2025, following an a-priori designed and prospectively registered protocol. Studies examining the retina using any non-interventional method of retinal assessment in women with GDM compared to non-GDM controls were identified. Potentially eligible studies included prospective and retrospective cohort, case-control and population-based studies, as well as randomized controlled trials. The Risk Of Bias In Non-randomized Studies of Interventions version 2 (ROBINS-I V2) tool was used to evaluate the risk of bias of the included studies. A meta-analysis was not performed due to considerable heterogeneity in the reported methods of retinal assessment, retinal parameters examined, disease severity, diagnostic criteria for GDM and gestational age at the time of retinal examination.

The electronic database search yielded 1326 results, of which 21 were eligible for full-text review and nine were included. Following citation screening for additional eligible studies, 10 studies were ultimately included in the systematic review. The methods of retinal assessment utilized in the included studies were cross-sectional and structural optical coherence tomography (OCT), optical coherence tomography angiography (OCTA) and retinal fundus photography. Each method examined various retinal structural and vascular parameters. Studies examining retinal vascular metrics using retinal fundus photography and cross-sectional OCT found similar retinal arteriolar parameters, increased retinal venular parameters and a reduced retinal arteriovenous ratio in women with GDM compared with normoglycemic controls. Studies utilizing structural OCT reported that the retinal nerve fiber layer (RNFL) thickness was decreased or similar in women with GDM vs non-GDM controls. Combinations of the ganglion cell layer (GCL) thickness, inner plexiform layer thickness and macular RNFL thickness were found to be lower in women with GDM. All studies reporting on other OCT parameters (acircularity index and retinal, macular and GCL thickness) found them to be similar between the two groups. The superficial and deep capillary plexus vessel densities, assessed using OCTA, were reported to be lower in women with GDM in some studies, whereas others found no significant difference between the two groups. For the remaining OCTA parameters (choriocapillaris vessel density, outer retinal vessel density, whole-image vessel density, foveal avascular zone area, foveal density and choriocapillaris flow area), no study identified significant differences between women with GDM and non-GDM controls. The ROBINS-I V2 tool found the risk of bias to be serious in six studies and moderate in four studies.

Existing studies provide inconsistent evidence to clearly establish retinal structural or functional changes in pregnancies complicated by GDM. Future large-scale prospective studies are required to confirm these findings and evaluate whether the retinal changes observed in GDM persist postpartum. Such evidence may clarify their potential role as biomarkers of cardiovascular insult severity and inform stratified surveillance. © 2026 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.