Aggressive blood sugar control slows diabetic eye disease progression

Intensive glycemic control may reduce the risk of retinopathy progression in people with type 2 diabetes by half, according to a National Eye Institute (NEI)-funded study.

The ACCORDION Eye Study was designed as a follow-up to the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study conducted from 2003 to 2009, which tested treatment strategies to reduce the risk of cardiovascular disease among patients with long-standing type 2 diabetes, including intensive glycemic control. Although intensive glycemic control failed to reduce cardiovascular disease risk, such as heart attack and stroke, therapy did reduce retinopathy progression by about one-third by the end of the ACCORD study.

According to the NEI, diabetic retinopathy is a complication of diabetes that can damage tiny blood vessels in the retina of the eye, and is the most common cause of vision loss among people with diabetes.

The ACCORDION Eye Study researchers assessed diabetic retinopathy progression in 1,310 participants from the previous ACCORD study 4 years after stopping intensive glucose-lowering therapy. The follow-up examination included stereoscopic fundus photographs, but no additional clinical data were collected.

The primary outcome of the ACCORDION Eye Study was progression of diabetic retinopathy by 3 or more steps on the ETDRS (Early Treatment Diabetic Retinopathy Study) scale based on the eye examinations and fundus photographs at year 8 compared to baseline in the ACCORD study.

“These findings show how important it is to advocate for the best glycemic control possible,” said lead author Emily Chew, MD, deputy director of the division of epidemiology and clinical applications at the NEI. “That could mean educating the medical team of the types or classes of drugs available for oral hypoglycemia, and the importance of using insulin when necessary, which may be very important for the entire body.”

At the beginning of the ACCORD study in 2003, the mean hemoglobin A1c (HbA1c) was 8.1% for the intensive glycemic control group and 8.2% for the standard treatment group and by the end of the study, the mean HbA1c decreased to 6.4% in the intensive group and 7.7% in the standard group. At the time the ACCORDION Eye Study was initiated in 2010, the HbA1c levels were once again similar between both groups (7.3% for the intensive group and 7.7% for the standard group). 

Although HbA1c levels were similar, results of the new ACCORDION Eye Study showed that diabetic retinopathy progressed from baseline to year 8 in 5.8% of patients with intensive treatment versus 12.7% with standard glucose-lowering treatment.

Based on the results, researchers concluded that intensive glycemic control generated lasting protection from progression of diabetic retinopathy even though the HbA1c levels were similar 8 years after randomization. Previous studies have reported similar findings, but this is the first study in people with type 2 diabetes of approximately 10 years duration and established cardiovascular disease that demonstrated this effect.

“Intensive glycemic control confers better protection from progression of diabetic retinopathy than any drug that has been tested for treatment of diabetic retinopathy,” Chew said. “I suggest they be familiar with the standard of care advocated by the American Diabetes Association [ADA], the preferred glycosylated A1c level of 7 or below. And they should educate their pharmacists and the medical team of this recommendation. This is important for both type 1 and type 2 diabetes.”

 Researchers also looked at the effects of blood pressure and dyslipidemia treatment on the progression of diabetic retinopathy. The results of the study were announced at the ADA annual meeting in June 2016.