Risk of Developing Glaucoma in Postmenopausal Women with Diabetes in Korea

In previous studies, the association between diabetes and glaucoma is controversial.

Glaucoma is an irreversible progression of visual field loss that can be asymptomatic at early stages. The mechanisms associating diabetes with glaucoma and the likelihood of diabetes causing glaucoma are unclear. However, diabetes is a known risk factor for many macrovascular and microvascular complications. Previous studies suggested that microvascular damage resulted from diabetes can impact the optic nerve, thus increasing the risk for glaucomatous damage. Additionally, hyperglycemia may increase the intraocular pressure, thus increasing the susceptibility to the onset of glaucoma. However, the association between diabetes and glaucoma is inconclusive in prior studies.

The study in this discussion is an Institutional Review Board-approved retrospective review of eligible patients utilizing the Korean National Health Insurance Service database, which includes data up to 97% of the nation’s population. The authors started the study by screening all 40 or older women who had received a standardized National Health Screen Program (a comprehensive check-up for insured patients) and breast cancer check-up in 2009. The study excluded subjects with previously diagnosed glaucoma before 2009, unnatural menopause, and those with missing menopausal status. The primary endpoint was the development of glaucoma after the index year, which was analyzed using the Cox proportional hazard regression analyses. The diabetes status was stratified into five categories: normal (no history of diabetes diagnosis), impaired fasting glucose (IFG), new onset of diabetes, diabetes treatment with oral hypoglycemic medication, and diabetes treated with insulin.

In the results, compared to patients without diabetes, the adjusted risk of incident glaucoma increased with diabetes status in all groups. The adjusted HR for IFG was 1.061 (95% CI 1.036 to 1.086), for new-onset diabetes was 1.151 (95% CI 1.086 to 1.220), for diabetes treated with oral hypoglycemic medication was 1.449 (95% CI 1.406 – 1.493), and for diabetes treated with insulin was 1.884 (95% CI 1.777 – 1.999) with p < 0.0001 for all four groups. Before adjustment, the risk for glaucoma is also significantly higher with the diabetes group. However, adjustment was made for multiple confounding factors, such as age, income, smoking, drinking, exercise, body mass index, reproductive factors, and hormone replacement therapy). The association between diabetes status and new-onset glaucoma is consistent in all subgroups: age, smoking status, drinking status, hypertension, and dyslipidemia.

In this national scale, longitudinal cohort study, the authors concluded that “type 2 diabetes was associated with an increased risk of glaucoma incidence” in  Korean adults with natural menopause. Of note, patients in the IFG group had a 6% risk of developing glaucoma, while patients with diabetes treated with insulin had a 88% risk of developing glaucoma. The incidence of glaucoma in patients with diabetes increased based on their diabetic status. Therefore, patients with diabetes should be screen frequently and early to prevent the late-stage diagnosis and burden of severe glaucoma. However, due to the nature of a retrospective study, the authors could not further assess the severity of diabetes (for example, control versus uncontrolled diabetes, glycosylated hemoglobin levels) nor the severity of glaucoma (for example, intraocular pressure measurements, visual feel ranges). Besides, the study only includes postmenopausal women in Korea; hence, the results cannot be extrapolated to other populations (men, younger women, non-Korean patients).

Practical Pearls:

• Postmenopausal women with diabetes have an increased risk of glaucoma development.
• Patients with diabetes who are insulin-dependent are at higher risk for glaucoma.
• Due to the nature of the study, these study findings are only applicable to postmenopausal Korean women.

References:

Jung, Younhea et al. “Association between diabetes status and subsequent onset of glaucoma in postmenopausal women.” Scientific reports vol. 11,1 18272. 14 Sep. 2021,

Nakamura, Makoto et al. “Diabetes mellitus as a risk factor for glaucomatous optic neuropathy.” Ophthalmologica. Journal international d’ophtalmologie. International journal of ophthalmology. Zeitschrift fur Augenheilkunde vol. 219,1 (2005): 1-10.

Ding Nguyen, PharmD Candidate, University of South Florida Taneja College of Pharmacy