A link between diabetes mellitus and glaucoma: Danish nationwide study

Purpose To determine the effect of anti-diabetic medication on glaucoma. Furthermore, to investigate if diabetic comorbidities and concomitant medications are associated with glaucoma in patients treated with anti-diabetic medication. Methods Retrospective nationwide cohort study, spanning a 16-year follow-up period. The National Danish Registry of Medicinal Products Statistics was used to identify all claimed prescriptions for glaucoma medication and anti-diabetic drugs. Comorbidities with diabetic retinopathy and diabetic nephropathy were identified using the ICD-10 classification and the Danish National Patient Register. Results A total of 6,343,747 individuals in the period 1996–2012 were included. The overall incidence rates of new-onset glaucoma were 0.07 and 0.36 per 1,000 person-years for the reference population and for diabetes mellitus, respectively. Patients treated with anti-diabetic drugs at any time during the study period had a significantly higher overall relative risk of glaucoma (RR = 5.11, p < 0.0001), even when controlling for age, gender, diabetic retinopathies and calendar year-fixed effects (RR = 2.05, p < 0.0001). For patients treated with anti-diabetic drugs, we found an increased hazard for development of glaucoma in patients with diabetic retinopathies (HR = 1.40) and joint complications with diabetic retinopathies and diabetic nephropathy (HR = 1.40). Furthermore, we found that concomitant antihypertensive medications were associated with an increased likelihood of glaucoma overall, while treatment with β-blocker and RAS, in combination, are associated with a significantly lower risk (HR = 0.87). Conclusions Use of anti-diabetic drugs is strongly associated with use of anti-glaucomatous drugs. Diabetic complication as well as concomitant antihypertensive medications affect the risk of glaucoma in patients treated with anti-diabetic drugs.