SGLT-2i users showed lower retinal vessel densities compared to non-users, though causality cannot be established due to the cross-sectional design, and these are described as 'hypothesis-generating observations.'
Key Findings
Results
Non-users of SGLT-2 inhibitors exhibited significantly higher deep capillary vascular density (DCVD) in multiple retinal regions compared to SGLT-2i users.
Higher DCVD was observed in the whole retina, parafovea, and perifovea regions in non-users (p < 0.05)
The study included 100 T2DM patients: 46 receiving SGLT-2i and 54 non-users
OCTA (optical coherence tomography angiography) was used to measure retinal microvascular parameters
The authors note these findings do not prove SGLT-2i adversely affects retinal microvasculature
Results
Non-users of SGLT-2 inhibitors had significantly higher superficial capillary vascular density (SCVD) in the perifovea compared to SGLT-2i users.
The difference in SCVD was statistically significant in the perifovea region (p < 0.05)
SCVD differences were not reported as significant in all retinal regions, only in the perifovea
SCVD was measured using OCTA as part of a comprehensive retinal evaluation
Results
Radial peripapillary capillary (RPC) densities in the inferior nasal and superior temporal regions were significantly higher in non-users of SGLT-2i.
Statistically significant differences were found in the inferior nasal and superior temporal regions (p < 0.05)
RPC density was measured as part of a comprehensive OCTA evaluation
These regional differences suggest spatially specific patterns in microvascular density differences between groups
Results
Visual acuity and central macular thickness (CMT) did not differ significantly between SGLT-2i users and non-users.
No statistically significant difference was reported in CMT between the two groups
No statistically significant difference was reported in visual acuity between the two groups
These findings suggest that any microvascular differences do not translate to detectable functional or structural macular changes in this cross-sectional sample
Results
The SGLT-2i group had significantly higher weight and BMI compared to non-users.
Differences in weight and BMI between groups were statistically significant (p < 0.01)
HbA1c was also recorded for both groups, though group differences in HbA1c were not highlighted as significant in the abstract
Higher BMI in the SGLT-2i group represents a potential confounding variable that may influence interpretation of retinal findings
Discussion
The study was designed as a cross-sectional study and the authors explicitly state that causality cannot be established from these findings.
The authors describe results as 'hypothesis-generating observations'
The authors state: 'these results do not prove SGLT-2i adversely affects retinal microvasculature'
The authors recommend 'prospective longitudinal studies to clarify whether these findings reflect actual treatment effects or underlying patient characteristics'
Study included 100 T2DM patients total across two sites of comparison
What This Means
This research suggests that patients with Type 2 diabetes who were taking SGLT-2 inhibitors (a common class of diabetes medication) had lower blood vessel density in certain regions of the retina—the light-sensitive tissue at the back of the eye—compared to patients who were not taking these medications. The researchers used a specialized imaging technology called optical coherence tomography angiography (OCTA) to measure tiny blood vessels in the retina of 100 diabetes patients, 46 of whom were on SGLT-2 inhibitors. Despite differences in vessel density, both groups had similar visual acuity and central retinal thickness, meaning no obvious vision-related functional differences were detected.
Importantly, the researchers caution that this study cannot prove the medications are causing these differences. Because the study compared two groups at a single point in time rather than following patients over time, other factors—such as the fact that SGLT-2i users in this study tended to have higher BMI—could explain the observed differences. The authors explicitly describe their results as 'hypothesis-generating observations' rather than evidence of harm.
This research matters because SGLT-2 inhibitors are increasingly prescribed not just for blood sugar control but also for their potential heart and kidney protective effects, and understanding their impact on small blood vessels like those in the retina is an important area of investigation. The study highlights the need for longer-term studies that follow patients over time to determine whether these retinal vessel differences are caused by the medication, reflect pre-existing differences between patient groups, or have any meaningful impact on eye health.
Castur S, Capar M, Sahin S, Castur L, Eksert S, Gonen B, et al.. (2026). Association between SGLT-2 inhibitor use and retinal microvascular parameters in patients with Type 2 diabetes mellitus: A cross-sectional study.. Journal of diabetes and its complications. https://doi.org/10.1016/j.jdiacomp.2026.109394