Common Diabetes Drug Linked to Site-Threatening Vision Complications

A June 2012 study published in the Archives of Internal Medicine (http://jamanetwork.com), presents strong evidence of a link between a popular treatment option for type 2 diabetes and a serious vision condition known as diabetic macular edema (DME).

The class of drugs, known as thiazolidinediones, has been recommended by the American Diabetes Association (ADA)(http://www.diabetes.org/) as a second-line therapy for treatment of patients with type 2 diabetes mellitus. In order to achieve target levels of glycemic control, the drug is often used in combination therapy with insulin or other oral agents. Popular formulations include Actos and Avandia. Previous case reports and analyses have highlighted the need for further investigation as increased incidents of DME, as well as other adverse effects such as bone fractures and bladder cancer, were reported in patients using this class of drug.

Diabetes and Eye SightDiabetic macular edema is a condition affecting the retina of the eye. Retinopathy, a common condition for people with diabetes, is caused by a swelling of the capillaries around the eye. Retinopathy can go undetected for some time as vision is not initially changed or affected. Yet, stemming from untreated retinopathy, the more serious condition of DME occurs when the weakened capillaries allow fluid to leak into the focusing part of the eye, or the macula. The macula then swells, and vision becomes blurred and eventually is lost entirely. Untreated, DME is a chronic, site-threatening condition.

This most recent study presents compelling evidence of the link between thiazolidinediones and DME. The authors reviewed the medical records of over 100,000 patients as they progressed through treatment for type 2 diabetes over a period of 10 years. The study summarizes that there does exist an increased risk for development of diabetic macular edema in diabetes patients who are taking thiazolidinediones. Furthermore, the risk is greater for those also using insulin as a combination therapy option. Risk also increases with the duration of the treatment.

Unfortunately, the early stages of DME often go undetected for long periods as many patients do not experience symptoms before the damage is done. A change in vision may not be noticed until the retina is already damaged beyond repair. In fact, in patients with type 2 diabetes, DME is the now the leading cause of blindness. For this reason, the study stresses the now increased importance of routine screening for DME in type 2 diabetes patients using thiazolidinediones.

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