Infection with a common virus may increase the risk of type 2 diabetes in older adults, a new study from the Netherlands suggests.
In the study, adults ages 85 and over who were infected with cytomegalovirus were about twice as likely to have type 2 diabetes compared with those not infected.
Cytomegalovirus is a type of herpes virus found in 50 to 80 percent of adults over age 40; most people experience no symptoms of the infection.
The findings suggest that cytomegalovirus infection plays a role in the development of type 2 diabetes in the elderly, the researchers said. However, the study found an association, not a cause-effect link.
While the findings are interesting, researchers need studies that follow people forward in time to find out whether the virus could cause Type 2 diabetes, said Dr. Rifka Schulman, an endocrinologist at the Long Island Jewish Medical Center in New Hyde Park, N.Y.
In addition, because the study was conducted in elderly people, the findings may not apply to other populations, Schulman said.
For now, well-established risk factors such as obesity, high blood pressure and lack of exercise should be considered the primary causes of type 2 diabetes, she said.
Linking diabetes and infection
Previous studies have linked cytomegalovirus and type 1 diabetes, but studies looking at the virus and type 2 diabetes have had inconsistent results. One previous study looked at a generally younger group of adults than the new study — between ages 45 and 84 — and found no link between cytomegalovirus infection and type 2 diabetes.
In the new study, the researcher analyzed information from 549 elderly adults in the Netherlands.
About 80 percent were infected with cytomegalovirus, and 15 percent had type 2 diabetes.
About 17 percent of those infected with cytomegalovirus had type 2 diabetes, whereas 7.9 percent of those without the virus had diabetes.
The findings held even after the researchers took into account factors that could affect the results, including participants' gender, income, education, smoking status and number of medications.
Behind the link
The researchers speculated that cytomegalovirus may predispose people to diabetes by harming cells of the pancreas. The pancreas produces insulin, a hormone that is critical for getting sugar (glucose) into cells. type 2 diabetes develops when the body becomes desensitized to insulin, and the pancreas cannot produce enough insulin to compensate.
It's also possible that type 2 diabetes impairs the immune system, and as a result, makes individuals vulnerable to cytomegalovirus infection. However, this explanation is not as likely, because people are often infected with cytomegalovirus in childhood, the researchers said.
It may be that cytomegalovirus infection increases diabetes risk only after years of infection, which could explain why earlier studies in younger adults did not find a link, the researchers said.
The study was published Aug. 27 in the journal Immunity and Aging.