Depression Strongly Linked to Risk of Diabetes
The evidence keeps mounting that depression's toll goes far beyond its cost to a person's mental state. A study published this week in the Archives of Internal Medicine shows that elderly adults who have untreated depression are about 60 percent more likely to develop diabetes than those who aren't depressed. The finding is significant, considering that about 2 million seniors are estimated to suffer from depression.
Previous research has suggested that a link exists, but "there was a question of which came first, the depression or the diabetes," says study leader Mercedes Carnethon, assistant professor of preventive medicine at Northwestern University Medical School in Chicago. Researchers also weren't sure whether the depression itself led to diabetes or whether it was the fact that depressed individuals are less likely to exercise or eat nutritiously. In the current analysis, more than 5,200 men and women over 65 filled out annual health surveys over 10 years, reporting symptoms of depression and whether they were taking diabetes medication. After accounting for physical activity, smoking, body weight, and alcohol intake, the study found that about 4.2 percent of those who reported strong symptoms of depression, either at the onset of the study or over the duration of the study, developed diabetes compared with 2.9 percent of happier folks. Moreover, those taking antidepressants did not have an increased diabetes risk.
"What this suggests is that there's something physiological going on that is common to both depression and diabetes," says Richard Rubin, president of the American Diabetes Association and an associate professor of medicine and pediatrics at Johns Hopkins University. The exact mechanism isn't known, but it could be that depression leads to elevated levels of the stress hormone cortisol, which increases blood glucose levels and causes more fat to collect around the abdominal area. Midsection fat, as opposed to fat on the hips and thighs, tends to be more metabolically active, wreaking damage on organs like the heart, liver, and pancreas. This process could also explain depression's link to heart disease and strokes.
Given the evidence from this and about a dozen other studies, Rubin thinks depression should now be considered a risk factor for adult-onset type 2 diabetes. Carnethon adds that doctors need to be extra vigilant to screen their older patients for depression during an annual physical. You can also do a self-evaluation on the National Mental Health Association's website.