Is diabetes a direct cause of glaucoma and how is it managed?

From the Guidelines

Diabetes is not a direct cause of glaucoma but is a significant risk factor for developing it, particularly neovascular glaucoma, as people with diabetes are approximately twice as likely to develop glaucoma compared to those without diabetes. Management of diabetes-related eye complications involves a dual approach: controlling blood glucose levels and specific glaucoma treatments. For diabetes management, patients should maintain HbA1c levels below 7% through medications like metformin (starting at 500mg daily, increasing to 1000mg twice daily as needed), insulin if required, and lifestyle modifications including regular exercise and a balanced diet, as recommended by the standards of medical care in diabetes-2019 1. For glaucoma management, treatment typically begins with prescription eye drops such as prostaglandin analogs (latanoprost 0.005%, once daily at bedtime), beta-blockers (timolol 0.5%, twice daily), or carbonic anhydrase inhibitors (dorzolamide 2%, three times daily). More advanced cases may require laser procedures like selective laser trabeculoplasty or surgical interventions such as trabeculectomy or drainage device implantation. Regular comprehensive eye exams are essential—annually for most diabetic patients and more frequently if glaucoma is present, as suggested by the standards of medical care in diabetes-2020 1. This combined approach is necessary because diabetes damages blood vessels throughout the body, including those in the eye, which can lead to increased intraocular pressure and optic nerve damage characteristic of glaucoma.

Some key points to consider in the management of diabetic patients at risk for glaucoma include:

• The importance of optimizing glycemic control to reduce the risk or slow the progression of diabetic retinopathy, as emphasized in the standards of medical care in diabetes-2019 1.
• The role of blood pressure and serum lipid control in reducing the risk or slowing the progression of diabetic retinopathy, as highlighted in the standards of medical care in diabetes-2019 1.
• The need for prompt referral to an ophthalmologist for patients with any level of macular edema, severe nonproliferative diabetic retinopathy, or any proliferative diabetic retinopathy, as recommended in the standards of medical care in diabetes-2020 1.
• The potential benefits of laser photocoagulation therapy and intravitreous injections of anti-vascular endothelial growth factor in reducing the risk of vision loss in patients with diabetic retinopathy, as discussed in the standards of medical care in diabetes-2020 1.

Overall, a comprehensive approach to managing diabetes and glaucoma is crucial to preventing vision loss and improving patient outcomes, as supported by the latest evidence from the standards of medical care in diabetes-2020 1 and other relevant guidelines.

From the Research

Relationship Between Diabetes and Glaucoma

• The presence of diabetes has been proposed as a risk factor for glaucoma, with some studies suggesting that diabetic eyes are at greater risk of injury from external stressors, such as elevated intraocular pressure 2.
• Diabetes may cause ganglion cell loss, which becomes additive to a glaucomatous ganglion cell injury, potentially increasing the risk of developing glaucoma 2.
• However, the relationship between diabetes and glaucoma remains controversial, with some studies showing an inconsistent association between the two conditions 3.

Management of Glaucoma in Diabetic Patients

• The management of glaucoma in diabetic patients may involve the use of ocular hypotensive agents, such as beta-blockers, prostaglandins, and alpha2-adrenergic agonists 4.
• Combination therapy may be indicated when the target pressure for an individual patient cannot be reached with monotherapy 4.
• Certain elements of diabetes may slow glaucoma progression, and diabetic treatment may concurrently be beneficial in glaucoma management 3.

Risk Factors for Glaucoma in Diabetic Patients

• The presence of diabetes and elevated fasting glucose levels are associated with elevated intraocular pressure, the primary risk factor for glaucomatous optic neuropathy 5.
• Diabetes, diabetes duration, and fasting glucose levels were associated with a significantly increased risk of glaucoma, and diabetes and fasting glucose levels were associated with slightly higher IOP 6.
• Routine evaluation for glaucoma in diabetic patients, particularly in the telemedicine setting, may become a reasonable consideration to reduce the risk of vision loss in these patients 5.