Bladder Cancer, Heart Disease, and, now, Blindness: Diabetic Macular Edema
This story isn't exactly new – it came out in the wake of an American Diabetes Association conference in San Diego in the summer of 2011 – but even now, several months later, relatively few people are aware of it.
Followers of this blog as well as almost anyone who has been treated with thiazolidinediones (drugs that reduce insulin resistance in cells – namely, Actos and Avandia) are well aware that these medications have been associated with elevated risk for bladder cancer and can exacerbate cardiac disease. What they may not know is that these medications can also cause blindness in the form of a condition called diabetic macular edema.
Diabetics suffering from both childhood-onset Type I and the more common Type II (for which Actos and Avandia are prescribed) are no stranger to the fact that they run a greater risk of blindness than the general population. Most commonly, this blindness is due to what is known as diabetic retinopathy, a condition that occurs when the delicate blood vessels at the back of the eye begin to leak, releasing blood and obscuring the field of vision. Although 80% of patients who have had diabetes for ten years or more develop this condition, it can be managed and even prevented in 90% of cases with proper treatment, surgery and tight glucose control.
Unfortunately, if part of that glucose control involves medication with thiazolidinediones, it can result in a different problem. Diabetic macular edema is a condition in which fluid begins to collect underneath the surface of the macula, the central part of the retina that plays a primary role in central vision as well as the ability to see color and fine details. As this fluid builds, it causes the macula to swell, which in turn leads to blurred vision. Normally, this can be treated with steroids or other anti-inflammatory medications.
Since Actos and Avandia are also known to cause fluid build-up in the lungs (pulmonary edema) and the extremities (peripheral edema), it should come as no surprise that a similar event could happen in other parts of the body as well. Complications from diabetes is the leading cause of blindness among adults in the U.S. British researcher, Dr. Richard Donelly, who conducted the diabetic macular edema study showing the connection between thiazolidinedione medications and macular edema, recommends that patients at risk for this condition avoid taking such prescriptions.
Interestingly, the risk of diabetic macular edema associated with Avandia was noted as early as 2007 in an article published in the journal Diabetes, Obesity and CVD News. The author's source for the information: Avandia's own warning label.
Law, Bridget Murray. “Avandia Study Gets Mixed Reviews.” DOC News, vol. 5 no. 1 (January 2008).
LoPatto, Elizabeth. “Takeda, Glaxo Diabetes Treatments Raise Risk of Eye Disease, Study Finds.” Bloomberg, 24 June 2011
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