Mild depression tied to diabetes complications

Even mild bouts of depression may worsen the health complications that often go along with type 2 diabetes, according to a new study.

Canadian researchers followed more than 1,000 patients for five years and found those who experienced multiple episodes of low-level depression were nearly three times more likely than those without depression to have greater disability, such as reduced mobility, poor self care and worse quality of life.

"Minor depression is a form of chronic stress," said Dr. Norbert Schmitz, associate professor of psychiatry at McGill University's Douglas Mental Health University Institute in Montreal, who led the study.

"Patients may not be able to follow treatment guidelines or they may have problems with diet, which in turn results in an increased risk of poor functioning," he said.

Diabetes can increase the risk of heart disease, nerve damage, kidney failure and blindness. The disease affects 25.8 million people in the U.S. and that number is expected to rise dramatically during the next 20 years, according to the Centers for Disease Control and Prevention.

Type 2 diabetes is often associated with obesity, but the elderly are also at high risk, with an estimated 27 percent of the over-65 population suffering from the disease.

Past research has found that nearly one-fifth of type-2 diabetics in the U.S. experience major depression, which is almost twice the rate seen in the general population. Some studies also link the combination of type 2 diabetes and depression with difficulty managing blood sugar levels and other health complications as well as increased risk of death.

Most research to date has focused on the role of major depression in poor health outcomes for diabetes patients, but Schmitz and his colleagues wanted to know if mild depression symptoms carried the same risks.

For their study, published in Diabetes Care, the researchers followed 1,064 adults, aged 18 to 80 years old, from the larger Montreal Diabetes and Well Being Study for five years.

The participants received a battery of surveys that assessed symptoms of depression, measures of disability, quality of life, diabetes-related health complications, social background, exercise and medical and psychiatric history, particularly related to treatment for depression.

The study team defined depression by a score based on symptoms experienced over a period of two weeks. While major depression would require at least five out of nine symptoms - such as appetite changes, fatigue and suicidal thinking - persisting over that time, mild depression would constitute fewer than five symptoms experienced at least once over the previous two weeks.

The researchers also looked at health-related quality of life, based on the individuals' own perceptions of how burdensome their health problems were, and translated into a number of "unhealthy days" the person reported over the past month.