People with type 2 diabetes who intensively controlled their blood sugar level during the landmark Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial Eye Study were found to have cut their risk of diabetic retinopathy in half in a follow-up analysis conducted four years after stopping intensive therapy. Investigators who led the ACCORD Follow-on Eye Study (ACCORDION) announced the results in New Orleans at the American Diabetes Association annual meeting. The study was supported by the National Institutes of Health’s National Eye Institute (NEI).
“This study sends a powerful message to people with type 2 diabetes who worry about losing vision,” said Emily Chew, M.D., deputy director of the NEI Division of Epidemiology and Clinical Applications and lead author of the study report, published online in Diabetes Care. “Well-controlled glycemia, or blood sugar level, has a positive, measurable, and lasting effect on eye health.”
A complication of diabetes, diabetic retinopathy can damage tiny blood vessels in the retina – the light-sensitive tissue in the back of the eye. ACCORDION is a follow-up assessment of diabetic retinopathy progression in 1,310 people who participated in ACCORD, which tested three treatment strategies to reduce the risk of cardiovascular disease among people with longstanding type 2 diabetes. ACCORD tested maintaining near-normal blood sugar levels (intensive glycemic control); improving blood lipid levels, such as lowering LDL “bad” cholesterol and triglycerides and raising HDL “good” cholesterol; and lowering blood pressure.
The treatment phase of the glycemic control portion of ACCORD had been planned to last 5.6 years but was stopped at 3.5 years due to an increase in death among participants in the intensive glycemic control group. The blood pressure and blood lipid portions of ACCORD continued. Tight control successfully reduced glycemia to an average 6.4-percent A1C – a measure of average blood glucose – compared to 7.7 percent among participants on standard glycemic control therapy.
Although it failed to reduce cardiovascular disease risk, such as heart attack and stroke, the researchers found that the therapy had cut retinopathy progression by about one-third by the end of ACCORD. Investigators considered progression to have occurred if a participant required laser surgery for diabetic retinopathy, required a vitrectomy–a procedure used to remove the gel-like fluid of the eye – or advanced three or more steps on the Early Treatment Diabetic Retinopathy Study (ETDRS) Severity Scale. The ETDRS Severity Scale uses photographs of the retina to rate disease severity from 1 (no disease) to 17 (high-risk for progression in both eyes).