Diabetes Linked to Significant Corneal Endothelial Changes

A study from a tertiary care center in India reported notable corneal changes in patients with type 2 diabetes, including increased central corneal thickness and altered endothelial morphology. Higher HbA1c levels and longer disease duration were linked to these findings. The authors emphasize that subtle endothelial dysfunction may precede clinical signs, supporting regular corneal assessment in diabetic patients. Photo: Francis W. Price Jr., MD. Click image to enlarge. Diabetes mellitus is a burden facing the healthcare community worldwide, estimated to affect over 285 million people. Persistent diabetes leads to microvascular and macrovascular complications, and the visual system is significantly vulnerable, including the retina, lens and cornea. Corneal erosions, punctate epithelial keratopathy and corneal ulcers are just a few of the corneal abnormalities found in patients with diabetes. In particular, increased central corneal thickness (CCT) in these patients may reflect subclinical corneal edema due to endothelial dysfunction, and research into the relationship between diabetes and corneal endothelium morphology and thickness is ongoing albeit variable. A study published recently in BMC Ophthalmology sought to compare specific corneal parameters in those with and without the disease and came to the conclusion that there are significant changes that may warrant regular monitoring.The cross-sectional comparative study was conducted at a tertiary care center in India between June 2024 and March 2025. A total of 100 adults between ages 40 and 60 were included and split into two groups based on diabetes status (present or absent). Those with diabetes were required to have a minimum disease duration of five years and only those with clear corneas were eligible. All participants underwent a comprehensive ophthalmological evaluation, including intraocular pressure measurement, refraction, best corrected visual acuity and slit-lamp biomicroscopy. Corneal endothelial imaging was performed using noncontact specular microscopy to assess CCT, endothelial cell density (ECD), coefficient of variation (CV) and hexagonality (HEX). According to the researchers, patients with diabetes had significantly higher CCT in both eyes (OD: 593.9μm; OS: 610.5μm) compared to those without the disease (OD: 550.9μm; OS: 593.9μm). HEX was lower in diabetes patients (OD: 43.2%; OS: 42.3%) vs. controls (OD: 52.1%; OS: 41.7%). CD and CV showed no significant differences. These findings suggest diabetes is associated with increased corneal thickness, reduced endothelial cell count and likelihood of loss of normal endothelial cell shape. There were some notable differences between patient sex mentioned by the researchers. In the diabetic group, CCT was found to be significantly higher in women compared to men in both the right eye and left eye. The mean CCT in the right eye for women was 605.2μm vs. 580.5μm for men. Similarly, in left eyes, women had a mean CCT of 627.6μm compared to 590.7μm in men. This indicates a statistically significant gender difference in corneal thickness among diabetic patients, with women having thicker corneas. “Taken together, our results align with the majority of published literature, which consistently reports that diabetic patients exhibit lower ECD, higher CV and reduced hexagonality compared to non-diabetic controls,” wrote the researchers in their paper. “These changes reflect progressive endothelial cell loss, polymegethism and pleomorphism, all of which compromise endothelial function and contribute to increased corneal thickness observed in diabetic patients.”The mean duration of diabetes in affected patients was 9.15 years and the mean HbA1c of 7.31% reflects long-term glycemic control. “The elevated HbA1c in our diabetic cohort also suggests that many participants had suboptimal glycemic control,” the researchers wrote. “Poor glycemic control, together with longer duration of diabetes, can accelerate endothelial cell loss, increase polymegethism and pleomorphism and influence central corneal thickness.”The statistical power and generalizability of the findings may be limited by the small sample size, according to the authors, who wrote that a larger cohort across different demographics could provide a more comprehensive understanding of these corneal alterations. The study was completed at a single care center, which may introduce selection bias, and the cross-sectional design only allowed for observations of associations at a specific point in time and does not permit conclusions regarding causality, they added. “Therefore, while changes in corneal endothelial parameters were noted in relation to diabetes, it remains unclear whether these are direct effects of disease duration or influenced by other confounding factors. Longitudinal studies are recommended to better establish temporal and causal relationships,” they wrote.Nevertheless, the authors concluded that these results highlight the importance of monitoring corneal parameters in patients with diabetes, particularly among those with long-standing or poorly controlled disease.Click here for the journal source. Sharma S, Madan VV, Banerjee S. Comparative study of corneal endothelial morphology and central corneal thickness in diabetic and non-diabetic patients at tertiary care centre. BMC Ophthalmol. November 13, 2025. [Epub ahead of print.] This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.