Statins May Prevent Diabetic Retinopathy in People with Diabetes

With Sunir Garg, MD, J. Michael Jumper, MD, and Eugene Yu-Chuan Kang, MD

The statin drug you are taking to lower your "bad" cholesterol may be doing more than protecting you from a higher risk of heart attack and stroke due to diabetes,1 according to new findings published in JAMA Ophthalmology.

"Statins may actually help patients' eyeballs as well, not just their hearts," says Sunir Garg, MD, FACS, a co-author of this study and professor of ophthalmology at the Wills Eye Hospital in Philadelphia, Pennsylvania. He is also co-director of the Retina Research Unit at the hospital and editor-in-chief of Retina Times.

The group taking a statin were less likely than those not on the cholesterol-lowering medication to need treatments for diabetic retinopathy, if it occurred.1

People with diabetes are at increased risk of vision loss.When individuals with diabetes take a statin, they are less likely to develop diabetic retinopathy. Photo: 123rf

Statin Therapy Reduces the Risk of Developing Diabetic Retinopathy

In the new study, Dr. Garg and his research team found that men and women with type 2 diabetes (T2D) who took a statin (a class of medications prescribed for high blood cholesterol) had a much lower risk of diabetic retinopathy, a complication of diabetes that can lead to vision loss or blindness, than those with diabetes who were not taking a statin.1 These patients also were less likely to need treatment for diabetic retinopathy if it did occur, he said.

Researchers followed more than 37,000 individuals in Taiwan for an average of seven years. Patients were in their early 60s, and about half of them were taking a statin cholesterol-lowering medication and half were not.1

What the investigators found was that 2,004 participants in the statin group and 2,269 in the non-statin group developed diabetic retinopathy, which was statistically significant, according to Dr. Garg. In fact,  when compared to the individuals who were not taking statin therapy, the statin group had an 8% lower likelihood than those not on statins of developing the non-aggressive form of diabetic retinopathy.1

The risk of developing diabetic retinopathy was even higher for the more advanced stage known as proliferative diabetic retinopathy; individuals receiving a statin were 36% less likely to develop the more aggressive form of eye disease.1 “So overall, we found, a reduced risk of 14% of developing diabetes-related eye disease in all patients receiving statins in comparison to those not on the cholesterol-lowering medication.1

If Diabetic Retinopathy Develops, Taking a Statin Means No Further Treatment Needed

The earlier stage of diabetic retinopathy is marked by visible damage to small blood vessels in the retina. Often, the blood vessels in people with this condition may leak fluid into the eye tissue, leading to retinal swelling or bleeding that can lead to vision loss. In the more advanced stage of eye disease, the retina grows abnormally large blood vessels, which may increase the risk of hemorrhages (bleeding) that results in sudden and severe vision loss. Having the more aggressive, proliferative diabetic retinopathy increases a person’s risk of retinal detachment, which can also lead to vision loss.2

Dr. Garg and his team found that those individuals receiving statin therapy were less likely to have the retinal detachment and swelling of the macula—the central area of the retina that when healthy assures that our vision remains clear, or 20/20.

These findings are great news for the majority of individuals (7 in 10, or 68%),3 who have diabetes and heart disease since it appears they may be able to avoid the difficult treatments required to manage diabetic retinopathy. The standard treatment for diabetes-related eye disease—an injection of medication into the eye, which typically causes distress—may be avoided in these patients, Dr. Garg tells EndocrineWeb. 

There may be many explanations for the reasons that the statins seem to prevent damage to the retina, but a reduction in inflammation is probably a major one. The statins, he says, predictably, also reduce the risk of heart attacks and for people with diabetes, they also experience less nerve damage and fewer foot ulcers.4,5

Results Gain Support from Diabetes Eye Specialist

"These findings confirm the growing body of knowledge that better control of blood glucose, blood pressure, and blood cholesterol all reduce the risk of diabetic complications," says J. Michael Jumper, MD, an ophthalmologist, and retina specialist at West Coast Retina Medical Group, San Francisco was not involved in the study. He is on the board of the American Society of Retina Specialists and agreed to review the study for EndocrineWeb.

Dr. Jumper says many people with cholesterol levels high enough to need treatment are not getting that treatment; doing so would potentially help their health, including eye health.

"My advice to patients is to discuss their cholesterol level with their primary care provider and to begin treatment with a statin if indicated," he tells EndocrineWeb.  People with diabetes who control blood sugar, cholesterol, and blood pressure as well as exercise regularly and avoid smoking have the best chance of preserving their vision and avoiding diabetic retinopathy, says Dr. Jumper. 

Benefits of Lipid-lowering Therapy for People with Heart Disease and Diabetes

"From this study, we are realizing that not only sugar control but also lipid [cholesterol] control play an important role in preventing diabetic retinopathy," says Eugene Yu-Chuan Kang, MD, the study lead author and a physician at Chang Gung Memorial Hospital in Taoyuan, Taiwan.  Dr. Kang suspects that while most people with diabetes pay attention to their blood sugar numbers, too few are as vigilant about doing what is necessary to control their blood cholesterol.

The study findings also indicate that patients who took their statin medication as instructed had even better results as far as their diabetic retinopathy than those who did take their prescription or follow their doctor's advice about cholesterol-lowering efforts, Dr. Kang says.

Other studies have found that statins, often combined with other medications that lower diabetes-related complications, so Dr. Garg suspected that the cholesterol-lowering drugs would help reduce diabetes-related eye disease too. In the new study, they found a benefit of lowering onset and progression of diabetic retinopathy with statins alone.1

Even though the study was done with people living in Taiwan,1 Dr. Garg says the results would apply to US patients as well, in response to a question posed by EndocrineWeb based on results from studies and reports; however, the older research mostly looked at statins in combination with other treatments. 

Last year, for instance, researchers looked at the results of eight clinical trials that compared those on cholesterol-lowering drugs (not only statins but other types of drugs) with those not taking a statin.They found that the cholesterol-lowering drugs slowed the progression of the diabetic retinopathy.

Statins Offer Benefits But Still Require Healthy Lifestyle Habits

The potential benefits of taking a statin should be viewed as a bonus but not a reason to neglect healthy habits, Dr. Garg says. "For people with diabetes and high cholesterol, the cornerstone [of your care] is still going to be following a diabetes-wise diet and getting regular exercise," he says, "because we know actively managing your blood cholesterol is critical in order to reduce the risk of having a heart attack and stroke.''

And, as good as the results appear, "if patients do not have high cholesterol, we don't know if the statins will be potentially helpful or not [for eye health]," he cautions.

So for individuals who have diabetes but have not been diagnosed with hyperlipidemia, you shouldn't think about asking your doctor for a statin prescription, he says, at least not yet. There is no data to support any advantage to taking a statin if you are taking it specifically to manage your risks for heart disease.

None of the doctors have any relevant financial conflicts regarding this study.

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