MONDAY, April 23, 2007 (HealthDay News) -- Depression appears to raise the odds for diabetes in older people, researchers report.
"Older adults who report high levels of depressive symptoms are more likely to develop diabetes over time than older adults who have lower depressive symptoms," said lead researcher Mercedes R. Carnethon, assistant professor of preventive medicine, at the Feinberg School of Medicine at Northwestern University.
"We need to carefully evaluate older adults for depressive symptoms, and they need to be taken seriously because of the potential impact," she added.
However, whether treating depression reduces the risk for developing diabetes isn't known, Carnethon said.
Her team published the findings in the April 23 issue of the Archives of Internal Medicine.
In the study, Carnethon's group collected data on almost 4,700 people 65 years of age and older who were not diabetic when the study began in 1989.
Over the following 10 years, participants were evaluated for symptoms of depression linked to changes in mood, irritability, calorie intake, concentration and sleep.
The researchers scored symptoms of depression on a scale of zero to 30, with scores of eight or higher indicating high levels of symptoms. When the study began, the average symptom score was 4.5. In addition, one-fifth of the people had a score of eight or higher.
During the 10 years of follow-up, half the people saw their scores increase by at least five points. In all, 234 study participants developed diabetes. The rate of diabetes was higher among those with a score of eight or more compared with those whose scores were below eight, Carnethon's team found.
Carnethon believes the link between depression and diabetes has several causes.
"One is behavioral," she said. "Individuals who are depressed may be less likely to engage in healthy physical activities that would protect against the development of diabetes. They may be less likely to sleep well, have healthy diets, all of which are risk factors for developing diabetes," she said.
There could also be biological factors at play. These include increased levels of blood markers of inflammation, such as C-reactive protein, which has been linked to both diabetes and depression, Carnethon said.
Another expert said more research is needed.
"This paper extends earlier findings of a relationship between depressive symptoms and increased risk of developing diabetes, by demonstrating that individuals with worsening depression or with persistent depression are also at increased risk of developing diabetes," said Lana Watkins, an associate professor in the department of psychiatry at Duke University Medical Center in Durham, N.C.
However, Watkins said the link remains unclear.
"In order to identify conclusively whether depression increases diabetes risk through excessive caloric consumption and/or through sedentary behavior, better measures of these two factors are needed," Watkins said.
For more information on depression and diabetes, visit the American Diabetes Association.