Having both depression and type 2 diabetes increases the risk of death for heart patients. Each factor had been known to increase the risk of heart disease deaths by itself, but together they're even more deadly.
In an analysis of more than 900 patients with established coronary artery disease, Duke University Medical Center psychologists found that those with both type 2 diabetes and symptoms of depression were more likely to die than heart patients without those conditions.
The study showed that among type 2 diabetes patients, having high depression scores increased the risk of dying by 20 to 30 percent compared to patients with similar depression scores but no type 2 diabetes.
"We found a trend showing that the probability of death increases as the level of depression increases in diabetic patients with coronary artery disease," said Duke researcher Anastasia Georgiades, Ph.D. "Our data appear to show an important interaction between type 2 diabetes and depression, meaning that physicians should closely monitor their heart patients who have both of these disorders."
"There is some sort of synergistic effect between type 2 diabetes and depression that we don't fully understand," Georgiades said. "In our analysis, we controlled for factors that could influence mortality, such as heart disease severity and age. For whatever reasons, these patients were still at higher risk of dying, and future research will aim to investigate the mechanisms for this association."
The research was supported by the National Heart, Lung, Blood Institute.
The researchers followed 933 heart patients for more than four years and correlated the 135 deaths that occurred during that period with the presence of type 2 diabetes and depression alone and together.
Georgiades said there are some possible explanations for the link between depression and diabetes.
"Patients with type 2 diabetes typically have an extensive self-care regimen involving special diet, medications, exercise and numerous appointments with their doctor," she said. "It may be that such patients who are depressed might not be as motivated to carry out all these activities, thereby putting them at higher risk."
Depression has also been linked to other cardiovascular risk factors such as insulin resistance, hypertension, obesity, increased cigarette smoking, alcohol abuse and physical inactivity.
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