Do people today see more poorly than they used to? And might soaring rates of diabetes have something to do with it?
Yes and yes. According to a new study from researchers in Denmark, children who were exposed to diabetes before birth had a 39% increased risk of developing vision problems, or what ophthalmologists called refractive error (RE), which is an umbrella term for nearsightedness (myopia), far-sightedness (hypermetropia), and astigmatism.
It’s well documented that peoples’ eyesight, especially nearsightedness, is worsening around the world, so much so that experts now speak of a “myopia epidemic.” In China, for example, it’s estimated that nine out of ten teenagers and young adults need glasses. And in the United States, according to the Vision Council of America, about three-quarters of adults now require some kind of vision correction, either eyeglasses or contact lenses.
Researchers mostly attribute this trend to two factors: spending too much time in front of screens and, especially, too little time in bright daylight. The new Danish study, however, which was published in the journal Diabetologia, suggests yet another factor: prenatal exposure to diabetes.
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Previous research had indicated that people with acute RE might have had eye defects even before birth — findings that suggested to the Danish analysts that the conditions to which an unborn child is exposed in the uterus might be a factor in the later development of eye problems. Specifically, they wondered if high blood sugar in women during pregnancy could lead to similar high blood sugar in the fetus, resulting in damage to the retina and the optic nerve as well as changes in the shape of the eyes.
For their analysis, the researchers utilized several national medical registers in Denmark and incorporated data on all the births in the country from 1977 to 2016 — a total of nearly 2 1/2 million. Some 2.3% of the children (56,419) were exposed to maternal diabetes before birth. Most (1.1%) were exposed to gestational diabetes, while type 1 affected 0.9% and type 2 affected 0.3%. Not surprisingly, given the rising rates of diabetes over the last few decades, the percentage of births by mothers with diabetes increased over the span of the study — from 0.4% in 1977 to 6.5% in 2016.
Increased risk of eye problems in children of mothers with diabetes
Follow-up began at birth and continued for most of the subjects until they were 25 (unless they were diagnosed with diabetes sooner, left the country, or died). Otherwise the study concluded in 2016. During this follow-up phase, high RE was diagnosed in 533 children of mothers with diabetes, and the researchers calculated that exposure to mothers’ diabetes increased the risk of high RE by 39%. There was a difference among the types of diabetes: With type 1, the risk was greater by 32% and with type 2 it was greater by 68%. As for mothers who suffered complications from diabetes (such as diabetic coma, ketoacidosis, and kidney, eye, nerve, and circulatory problems), their children were twice as likely to have eye trouble.
As for types of RE, the researchers reported a 34% greater risk of nearsightedness, a 37% greater risk of far-sightedness, and a 58% higher risk of astigmatism. As the authors summed up their findings, “ … we observed that children born to mothers with either pre-gestational diabetes or gestational diabetes were at an increased risk of developing high RE in general, as well as specific types of RE, persisting from the neonatal period to early adulthood. Children born to mothers with diabetic complications had the highest risk of high RE.”
As for the explanation of the connection between diabetes in mothers and eye trouble in their children, the researchers speculated that high blood sugar levels in the fetus might cause what they termed “oxidative stress” (a condition caused by low levels of antioxidants) and/or inflammation, and these lead to eye damage. Also, high blood sugar levels in the fetus might cause nerve damage and a condition known as endothelial dysfunction, in which the lining of the small arteries don’t function properly.
Whatever the link, the researchers recommend early screening for eye trouble in the children of mothers with diabetes. As they explained, “As many REs in young children are treatable, early identification and intervention can have a lifelong positive impact.”
Want to learn more about keeping your eyes healthy with diabetes? Read “Diabetic Eye Exams: What to Know,” “Eating for Better Vision and Healthy Eyes,” and “Keeping Your Eyes Healthy” and watch “Diabetes and Your Eyes.”