Diabetes, prediabetes, and the risk of glaucoma

This study examined the association between diabetes, prediabetes, and glaucoma (increased pressure in the eye that leads to vision loss).

The high blood glucose (sugar) levels found with diabetes are associated with many ocular (eye) complications, including retinopathy (damage to the blood vessels of the eye), cataracts (cloudy patches develop on the eye lens), and uveitis (swelling and irritation to the middle layers of the eye). However, the association between diabetes and glaucoma is less clear.

One meta-analysis (an analysis of data from multiple studies) determined there was a 50% increase in the risk of glaucoma for diabetics but other studies have found no relationship between the two disorders. It is also unclear whether patients with prediabetes (blood glucose levels that are higher than normal but not high enough to be classified as diabetes) have an increased risk of glaucoma.

The current study examined the relationship between diabetes, prediabetes, and glaucoma. The study examined 3,026 patients who took part in a National Health and Nutrition Examination Survey. The survey included a questionnaire and detailed physical exam including blood pressure and fasting blood glucose levels (levels of glucose following a period without food or drink). Patients were defined as diabetic or prediabetic based on self-reporting or fasting blood glucose levels, and to have glaucoma based on prior diagnosis by an eye doctor.

Of the 3,026 patients, 17.1% were determined to have diabetes and 49% to have prediabetes. Glaucoma was found in 9.5% of diabetics, 3.5% of prediabetics, and 2.6% of patients with normal blood glucose levels. Patients with diabetes had an 80% higher risk of having glaucoma as did other patients. Patients with diabetes for longer periods (more than 5 years) had a 3.9-fold increase in the risk of glaucoma compared to patients with diabetes for shorter periods (less than 5 years).

This study concluded that patients with diabetes, particularly long-standing diabetes, have a higher prevalence of glaucoma than do patients with prediabetes or normal glucose levels.