So-called nonrefractive vision impairment - which includes glaucoma and cataracts - can't be corrected with glasses, and typically requires laser therapy or surgery. It can also lead to permanent vision loss in some cases, especially when the problem isn't identified or treated in a timely fashion.
The researchers said that as diabetes rates continue to rise - and hit younger and younger people - some complications tied to the disease are expected to spike as well. Vision loss is especially a concern among people who have had diabetes for ten years or more.
Using data from a national health and nutrition study, Friedman's team found 1.4 percent of the 9,471 adults examined in 1999 through 2002 had nonrefractive vision impairment. That compared to 1.7 percent of the 10,480 people tested in 2005 through 2008.
Over that time, the number of study subjects who'd had diabetes for at least ten years also increased, from 2.8 percent to 3.6 percent. Among adults younger than 40, that figure more than doubled - from 0.3 percent to 0.7 percent.
The study can't prove diabetes was behind the rise in vision problems.
However, everything else linked to a higher risk of nonrefractive vision impairment - such as poverty and lack of education - was the same or better in the later study population compared to the earlier one, the researchers wrote Tuesday in the Journal of the American Medical Association.
"The only (association) that got worse and got dramatically worse is diabetes, and not just diabetes, but diabetes for a long time," Friedman told Reuters Health.
'A REALLY ALARMING SIGN'
Vision problems related to diabetes develop when fluid accumulates in the retina, making it blurry, or when new blood vessels grow in the back of the eye due to lack of oxygen.
The type of vision loss measured in the study - worse than 20/40 in both eyes - isn't blindness, according to Friedman, but would make it harder for people to live independently and would mean many couldn't get an unrestricted driver's license.
"This is a really alarming sign," said David Musch, an epidemiologist at the University of Michigan Kellogg Eye Center in Ann Arbor, who co-wrote an editorial published with the study.
"This is probably only one of a number of signs that will be evident in the near future if we continue to have young children and adolescents be overweight and obese," he told Reuters Health, noting that more kids and adolescents are being diagnosed with what used to be considered "adult-onset" diabetes.
"This is a message to vision care providers that they're going to be seeing a lot more of these complications among a younger population," Musch added.
Friedman said screening everyone with diabetes for vision problems, as is done in England, can almost completely eliminate blindness related to the condition. However, only about half of diabetics in the U.S. currently get their eyes checked regularly.
"Hopefully what this article will do is raise awareness and in part increase the screening rate," he said.
SOURCE: http://bit.ly/JjFzqx Journal of the American Medical Association, online December 11, 2012.