Race and Retinopathy

Can a person’s race or ethnicity affect his or her chances of going blind? If that person has diabetes, they answer is yes, according to a study just published in the journal JAMA Ophthalmology.

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The most common cause of blindness in adult Americans is diabetic retinopathy — a condition that occurs when high blood sugar levels damage blood vessels in the retina, a light-sensitive membrane at the back of the eye. Clearly, then, keeping blood sugar levels under control is key to preventing retinopathy. But at what point do blood sugar levels make the condition more likely? This new study indicates that the optimal blood sugar thresholds for predicting retinopathy vary among whites, blacks and Hispanics.

The researchers used data taken from the National Health and Nutrition Examination Survey (NHANES), a program of studies organized by the U.S. National Center for Health Statistics that’s designed to evaluate the health and nutritional status of Americans. The data the researchers used came from 3,003 whites, 1,215 Hispanics and 1,084 non-Hispanic blacks. Of all the individuals in the three groups, 661 showed evidence of diabetic retinopathy.

To determine the risk of retinopathy, the researchers used what’s known as the hemoglobin A1c (HbA1c) threshold. According to the American Diabetes Association, an HbA1c threshold of 6.5 percent indicates the presence of diabetes, but the researchers discovered that the optimal predictive HbA1c threshold for retinopathy was different for the three groups — 6 percent for whites, 6.4 percent for Hispanics and 6.5 percent for blacks.

Study authors Kevin J. Moore, MD, MPH, Erin C. Dunn, MD, MPH, and Tulay Koru-Sengul, PhD, MHS, noted that, “Glycemic control may affect diabetic retinopathy risk differently across race/ethnicity,” and they said the next phase of their research will be to explore “which other sociodemographic variables influence diabetic retinopathy risk.” They also pointed out that their study indicates that even if a person’s diabetes is under control, that “does not rule out” a risk of diabetic retinopathy.

Overall, they concluded, “We hope that these thresholds emphasize the importance of routine ophthalmologic care among diabetics.” It’s an important point. According to the National Eye Institute, the number of Americans with diabetic retinopathy is expected to nearly double between 2010 and 2050 — from 7.7 million to 14.6 million.

Want to learn more about diabetes and eye health? Read “Keeping Your Eyes Healthy,” “Foods for Healthy Eyes” and “Diabetes and Your Eyes — More Than Retinopathy.”

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