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Member Research and Reports

UNC Study Finds Diabetes Drug Therapy Does Not Increase Risk for Diabetic Retinopathy

New research on the impact of incretin-based therapies (IBTs) in older adults with diabetes shows this type of therapy may not increase the risk for diabetic retinopathy, a complication of diabetes that threatens sight.

The paper, “Incretin-Based Therapies and Diabetic Retinopathy: Real-World Evidence in Older U.S. Adults,” was published online July 16 in Diabetes Care and is a collaboration between researchers at the University of North Carolina Gillings School of Global Public Health and the UNC School of Medicine.

For the study group, the research team used a nationwide 20 percent random sample of fee-for-service U.S. Medicare beneficiaries ages 65 years and older with Parts A, B and D coverage between 2007 and 2015. This data resource is available to all UNC researchers and was originally started by a Gillings Innovation Laboratory.

The resource is funded currently by the UNC Center for Pharmacoepidemiology, the Gillings School’s Department of Epidemiology, the N.C. Translational and Clinical Sciences Institute, the Cecil G. Sheps Center for Health Services Research and the UNC School of Medicine.

The researchers selected individuals with no prior treatment for retinopathy that initiated different antidiabetic treatment options for controlling blood glucose, including IBTs, and studied how many developed retinopathy requiring medical treatment.

Co-author Dr. Til Stürmer, Nancy A. Dreyer Distinguished Professor and chair of epidemiology in the Gillings School, said the finding on the safety of IBTs helps clarify the results from previous studies on the impact of these drugs on the health of patients’ eyes – and points providers to the best therapies for their patients.

“Clinicians and patients constantly need to weigh benefit and harm of alternative antidiabetic treatments,” Dr. Stürmer said. “Our results add to the evidence base for these decisions.”

IBTs, including both oral DPP-4 inhibitors and injection GLP-1 receptor agonists, have been available for more than a decade. The DPP-4 inhibitors are the most highly prescribed brand-name oral diabetes agents. Some of the GLP-1 receptor agonists recently were shown to reduce the risk of heart attack, stroke and cardiovascular mortality, but recent large trials had observed a possible risk for retinopathy associated with IBTs.

However, these published trials were not designed systematically for assessing retinopathy complications. The research team’s findings that patients treated with IBTs did not have a higher incidence of retinopathy compared with alternative drug classes add to the evidence base required by physicians to make prescribing decisions, as it appears IBTs need not be avoided based on concerns about retinopathy.

Controlling blood glucose levels in patients with Type 2 diabetes is important to the management of the disease and reduces the risk of developing complications such as vision loss. Diabetic retinopathy is caused by damage to the blood vessels in the tissue at the back of the eye (retina) and is the leading cause of vision loss in adults.

In addition to retinopathy and vision loss, patients with Type 2 diabetes are more likely to develop cataracts and glaucoma than are people without diabetes. Therefore, all patients with diabetes should have an annual dilated eye exam – and early treatment if worrisome findings emerge over time.

Among patients with Type 2 diabetes, predictors for vision complications include age, diabetes duration, chronic hyperglycemia (uncontrolled blood sugar), nephropathy, hypertension, dyslipidemia, family history of eye complications, and eye injury or diseases.

Other Gillings School co-authors, all from the Department of Epidemiology, are Dr. Tiansheng Wang, doctoral student; Dr. Emily Gower, associate professor; Dr. Jin-Liern Hong, research collaborator; and Ms. Virginia Pate, applications analyst. Co-authors from the School of Medicine include Dr. John Buse, Verne S. Caviness Distinguished Professor and chief of the Division of Endocrinology, and Dr. Seema Garg, associate professor in the Department of Ophthalmology.

[Photo: Controlling blood glucose levels in patients with Type 2 diabetes is important to the management of the disease and reduces the risk of developing complications such as vision loss. Photo courtesy Public Domain Images]

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