TUESDAY, June 17 (HealthDay News) -- The relationship between diabetes and depression apparently cuts both ways: Not only are people with treated type 2 diabetes at a heightened risk for developing depression, individuals with depression are also at risk for developing diabetes.

The research revelation suggests that both doctors and patients need to be more aware of the dual risks.

"Doctors should have their sensitivity increased toward picking up on the potential for more of their diabetes patients and more of their depression patients having susceptibility to the other disorder," said Dr. Stuart Weiss, assistant clinical professor of medicine at New York University School of Medicine.

Type 2 diabetes and clinical depression tend to go hand in hand, the study authors said, although the question has been, which comes first?

"There have been studies that show people with diabetes are twice as likely to have symptoms of depression as those who don't, and it could either be because depression itself leads to the development of type 2 diabetes or it could be that having diabetes leads to the development of depression," said study lead author Dr. Sherita Hill Golden, an associate professor of medicine and epidemiology at Johns Hopkins University School of Medicine.

"There are several studies showing that depression and depressive symptoms lead to the development of type 2 diabetes, but only a couple of studies showing that diabetes itself leads to depression. We wanted to look to see whether or not we could tease out the chicken-and-egg situation," she said.

Previous studies have also found that treating depression can help extend the lives of people with diabetes.

The authors of the new study performed two analyses, both using information from participants in the Multi-Ethnic Study of Atherosclerosis trial.

The first analysis involved 5,201 individuals without type 2 diabetes at the start of the trail and found that treated type 2 diabetes was associated with a 54 percent increased risk of developing depressive symptoms over 3.2 years. Persons with untreated diabetes were not at risk of developing depression.

Interestingly, people with pre-diabetes or untreated diabetes were about 25 percent less likely to develop depressive symptoms than people with normal fasting blood sugar levels, the researchers said.

"That was a little bit of a surprise," Golden said. The study authors aren't sure why this was so, but suggest that maybe the monitoring associated with treating diabetes might contribute to depression.

The second analysis included 4,847 participants and found that elevated depressive symptoms were associated with a 42 percent greater likelihood of developing diabetes during the follow-up period. The stronger the depressive symptoms, the higher the chance of developing diabetes. After adjusting for such factors as being overweight, not exercising and smoking, the risk of developing diabetes was still 34 percent higher in patients with depression.

"Those with depression are more likely to consume more calories, be less physically active and are more likely to smoke, so they just have poor overall health behaviors in general," Golden said. "That seems to be one component of treating depression that needs to be addressed."

The findings, published in the June 18 issue of the Journal of the American Medical Association, indicate that integration of care may be helpful to these patients, Golden said.

"For people who are being treated for symptoms of depression, it's important also to think about some treatment modalities that can also help them adopt healthy behaviors," she said. "And certainly among people who have treated diabetes and who are at risk of developing depression, we need to be aware of that increased risk."

Golden serves on the Merck & Co.'s clinical diabetes advisory board; the study was supported by the U.S. National Institutes of Health.

More information

Visit the American Diabetes Association for more on type 2 diabetes and depression.