In one national sample of Americans, for example, close to half of adults with diabetes had some degree of hearing loss compared with about 20 percent of their diabetes-free counterparts.
Across the studies, neither age nor exposure to a noisy workplace explained the connection between diabetes and hearing loss, said Chika Horikawa, a dietitian at Niigata University in Japan, who led the analysis.
There could still be explanations other than diabetes itself, Horikawa said. Certain medications many diabetics take, particularly blood-pressure-lowering diuretics, can affect hearing, Horikawa noted.
Another limit of the analysis, Zonszein said, is that many studies did not differentiate between people with type 1 and type 2 diabetes. Type 2 diabetes, which often is related to aging and obesity, is far more common than type 1, which is an immune-system disease that usually arises at a young age.
Still, Horikawa said, the findings suggest it may be a good idea for people with any form of diabetes to have their hearing tested. Some research suggests that hearing loss may increase the odds of depression and dementia, potentially adding an even greater load to the burden of diabetes.
In reality, routine screening is done infrequently. Primary care doctors may not even ask diabetic patients about their hearing, Zonszein said.
"We're not very good at detecting this during routine office visits," he said.
Diabetes is tied to a range of complications, including heart disease, kidney failure and vision loss from damage to the eyes' blood vessels.
During office visits, doctors usually focus on bigger-picture things such as overall blood sugar control, diet and weight control, Zonszein explained.
Routinely sending patients without obvious hearing problems for a screening test "might sound simple, but, practically speaking, it's difficult," Zonszein noted. People wou
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