Depression May Up Type 2 Diabetes Death Risk

Oct. 27, 2005 -- People with type 2 diabetes may want to take special care to note and treat any depression they experience -- no matter how mild or serious it is.

A new study of people with type 2 diabetes shows a higher death rate among depressed patients over a three-year period.

The higher death rates were seen in patients with minor depression and those with major depression.

The researchers included Professor Wayne Katon, MD. He's the vice chairman of the University of Washington's psychiatry and behavioral sciences department.

The study appears in Diabetes Care.

Depression Is Common

Depression is widespread in the U.S. Every year, more than 9% of U.S. adults experience depression, according to the National Institutes of Mental Health (NIMH).

People with diabetes, like anyone else, can become depressed. Between 11% and 15% of people with type 2 diabetes have depression, notes Katon's team.

Depression can affect the body as well as thoughts and emotions. For instance, depression has been found to worsen heart disease and hamper survival in heart attack patients.

Major depression requires patients to have at least two weeks of five or more symptoms present for more than half the days, with at least one of the symptoms being depression. These symptoms interfere with the ability to work, study, sleep, eat, and enjoy once-pleasurable activities.

Minor depression requires two to four depressive symptoms for more than half the days for at least two weeks, with at least one of the symptoms being depression.

Now, Katon's study suggests that depression may also raise the risk of death in people with diabetes.

Tracking Depression and Diabetes

Katon's study included more than 4,100 people with type 2 diabetes. They lived in or near Seattle and were members of the same large HMO (health maintenance organization).

The patients completed mailed surveys that screened for depression. Then, they were followed for three years. Deaths from any cause were recorded.

The surveys showed major depression in nearly 500 patients and minor depression in 354 patients.

Here's what those terms meant in this study:

• Major depression: Having at least five depression symptoms for most of two weeks
• Minor depression: Having two to four symptoms for the same amount of time

Symptoms had to include depressed mood or loss of pleasure (anhedonia).

Higher Death Rate With Depression

Depressed patients had higher death rates during the three-year study.

• Eight percent of those without depression died (275 out of about 3,300 patients).
• More than 13% of those with minor depression died (48 out of 354 patients).
• About 12% of those with major depression died (59 out of nearly 500 patients).

The reasons for the pattern could be biological and behavioral, the researchers note.

They point out that depression has been linked to unhealthy behaviors (like being physically inactive and not taking medication), as well as serious health problems (including heart attacks).

Study's Limits

The study shows a pattern, but it doesn't pinpoint depression (or diabetes) as the cause of death.

Depression was only measured once, at the study's start. It's not known if patients became more or less depressed over time.

Plus, the groups weren't exactly alike. For instance, depressed people were more likely to smoke and to get little exercise compared with those who weren't depressed.

Depression is often treatable. The first step is asking for help. This study doesn't note which, if any, depressed patients sought treatment.