In high-risk adults with type 2 diabetes mellitus, two therapies may slow the progression of diabetic retinopathy.
Intensive blood glucose control reduced the progression of diabetic retinopathy compared with standard blood glucose control, and combination lipid therapy with a fibrate and statin also reduced disease progression compared with statin therapy alone. However, intensive blood pressure control provided no additional benefit to patients compared with standard blood pressure control.
The Action to Control Cardiovascular Risk in Diabetes ( ACCORD ) Eye Study was a landmark clinical trial that included 10,251 adults with type 2 diabetes who were at especially high risk for myocardial infarction, stroke or cardiovascular death. The study evaluated three intensive strategies compared with standard treatments for lowering cardiovascular risks associated with diabetes.
Intensive treatments included control of blood glucose to near normal levels, control of blood pressure to normal levels, and combination treatment of multiple blood lipids with Fenofibrate ( Tricor ) and Simvastatin compared ( Zocor ) to standard treatment with Simvastatin alone.
Fenofibrate treatment lowers triglycerides and raises HDL cholesterol levels, while Simvastatin lowers LDL cholesterol levels. All participants were enrolled in the blood glucose trial and in either the blood pressure or lipid trial.
The ACCORD Eye Study involved a subset of 2,856 participants. Researchers analyzed the effects of the treatment strategies on blood vessels in the eye by identifying diabetic retinopathy progression over four years.
Diabetic retinopathy is a disease in which blood vessels in the eye's light-sensitive retinal tissue are damaged by diabetes. Blood vessels can begin to leak, causing swelling in the retina, and abnormal new blood vessels can develop, both causing vision loss. In the study, disease progression was identified through retinal photographs that indicated blood vessel changes or by the need for laser or eye surgery to treat abnormal blood vessels.
Compared with standard blood glucose control, intensive control decreased the progression of diabetic retinopathy by about one-third, from 10.4 percent to 7.3 percent, over four years. Participants in the intensive control group had a median blood glucose level of 6.4 percent hemoglobin A1c, a level close to values in people without diabetes. The standard blood glucose control group maintained a median level of 7.5 percent.
In addition, compared with Simvastatin treatment alone, combination lipid therapy with Fenofibrate plus Simvastatin also reduced disease progression by about one-third, from 10.2 percent to 6.5 percent, over four years. No prior clinical trial has shown that the combination of Fenofibrate and Simvastatin reduces diabetic eye disease progression.
There were no differences in diabetic retinopathy progression among participants treated to an intensive systolic blood pressure target of less than 120 mm Hg compared with those treated to a standard target of less than 140 mm Hg.
In the main ACCORD study, none of the three treatment strategies resulted in a significant decrease in the combined rates of myocardial infarction, stroke or cardiovascular death compared with standard treatments. However, over about three-and-a-half years of follow up, participants in the intensive blood glucose group had a 22 percent higher risk of death ( 5.0 percent versus 4.0 percent ) and a three times higher risk of seriously low blood glucose ( 10.5 percent versus 3.5 percent ) compared with participants in the standard blood glucose control group.
The ACCORD study began in 2001, and participants were treated and monitored for an average of five years. Results of the blood glucose clinical trial were reported in 2008, when the intensive blood glucose therapy was stopped 18 months early due to an increased risk of death in the treatment group compared with the standard blood glucose control group.
Source: NIH - National Eye Institute, 2010
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