Statins are already a common therapy among patients with type 2 diabetes. Its cholesterol-lowering benefits may help retain patient vision longer.
Signs and symptoms of diabetic retinopathy—the leading cause of vision loss in persons aged 20 to 74 years—are prevalent in about one-third of patients with type 2 diabetes (T2D), according to a 2015 study. Investigators estimate this rate will likely rise in the following years.
Individuals with diabetes are also prone to high cholesterol, which can be managed with the use of statins. These statins may be providing the unintended benefit of decreasing the risk of developing certain diabetes complications including retinopathy. Still, investigators wrote, “the effectiveness of regular statin therapy as the primary prevention of the development of retinopathy in patients with diabetes remains uncertain.”
To clarify the connection between the drugs designed to lower cholesterol levels and the development of diabetic retinopathy, Eugene Yu-Chuan Kang, MD, from the Chang Gung Memorial Hospital in Taiwan and his team turned to the National Health Insurance Research Database.
They found 1,648,305 patients with type 2 diabetes on the registry between January 1, 1998 and December 31, 2013. Of those patients, 219,359 were eligible for the study. Patients were randomized 1:1 to either receive statin or serve as control. They followed up with patients after at least 7 years (mean 7.6 years for the statin group; 7.3 years for the non-statin group).
By the end of the study, 4273 patients had developed diabetic retinopathy, including 10.6% of patients from the statin group, and 12.0% of the non-statin group. Patients in the statin group also had significantly lower rates of macular edema and required fewer surgical and laser interventions, suggesting statin therapy could also slow the progression of diabetic retinopathy in patients that did have it, as was suggested by previously by the ACCORD study.
The investigators found that the protective effects of statins were dose and adherence-dependent. They divided the statin patients into three groups based on the dose and frequency with which it was taken as recommended by the 2013 American College of Cardiology/American Heart Association guideline.
The groups included patients on a low-intensity, medium-intensity, or high-intensity statin regimen. Those with the high-intensity statins had only a 3.4% likelihood of developing diabetic retinopathy, where the medium a low-intensity groups had a 6.0% and 13.4% chance, respectively.
“We found that statins could delay all stages of diabetic retinopathy and decrease the number of invasive procedures needed,” investigators wrote. “This finding was associated with the intensity and duration of statin use.”
Therefore, Kang and colleagues noted, improved medical management could not only reduce diabetes complications but also decrease the supplemental cost of eventual invasive interventions, including retina laser treatment, intravitreal injections, and vitrectomies.
The study, Association of Statin Therapy With Prevention of Vision-Threatening Diabetic Retinopathy, was published online in JAMA Ophthalmology.