People with type 2 diabetes who are treated with long-term insulin therapy run the risk of developing a thickening of the retina that can lead to blindness. Now, researchers believe they may be able to prevent the condition that leads to the loss of vision in these patients with use of a drug that can prevent damage from occurring to the retinal nerve.

Researchers from the Cleveland Clinic, the University of Wisconsin, and Case Western Reserve University are trying to tackle one of the leading causes of blindness in patients with type 2 diabetes. These patients often develop diabetic macular edema, a condition in which the retina thickens due to increased leakiness of blood vessels that normally surround and protect the retinal nerve. They presented their work at the American Society for Cell Biology’s Annual Meeting in San Francisco December 17.

Long-term insulin treatment may spur the onset of diabetic macular edema, prompting the research team to model and evaluate, in mice, the harmful effects of insulin on the blood vessels of the eye.

In the retinas of diabetic mice given insulin, levels of a form of the epidermal growth factor known as betacellulin, or Btc, spike upwards. Btc is known to increase the leakiness of retina blood vessels, so it could be a contributing factor to macular edema.

The researchers used short interfering RNA to block production of Btc and found that those animals had reduced retina leakiness in response to insulin dosing. Researchers went one step further and exchanged the short interfering RNA for a more clinically practical Btc-targeted EGF inhibitor, and got a similar result. In doing so, they showed that combination therapy of insulin and EGF inhibition may be useful in the prevention of macular edema in diabetic patients.

If any clinical trial moves forward with positive results, it would be welcome by the 4.2 million Americans with diabetic retinopathy, 675,000 of whom are at risk of progressing to diabetic macular edema, according to The National Diabetes Information Clearinghouse.