A new study has suggested that older women who suffer from both diabetes and depression are at a higher risk of dying from all causes, including heart disease, over a six-year period.
In fact, symptoms of depression affect between one-fifth and one-fourth of patients with diabetes, nearly twice as many as individuals without diabetes.
An Pan of the Harvard School of Public Health, Boston, and colleagues looked at 78,282 women aged 54 to 79 in 2000 who were participating in the Nurses' Health Study.
Women in the study were confirmed to be type II diabetes via questionnaires. They were classified as having depression by diagnosis, were treated with antidepressants or scored high on an index measuring depressive symptoms.
During the six-year follow up, the researchers found a 44 percent increased risk of dying from cardiovascular among women with depression and a 35 percent increased death risk among women with diabetes, compared to those who had neither.
For cardiovascular disease alone, women with diabetes had a 67 percent higher risk of death, women with depression had a 37 percent increased risk and women with both had a 2.7-fold increased risk.
The authors say the reasons are unclear, but perhaps depression leads to poor glycemic control and failure to control diabetes that leads to complications.
Diabetes and depression are both linked to unhealthy behaviours such as poor diet, smoking and a sedentary lifestyle, they added.
They also speculate that depression might be linked to higher death rates in women because of changes in the nervous system that affect the heart.
"Considering the size of the population that could be affected by these two prevalent disorders, further consideration is required to design strategies aimed to provide adequate psychological management and support among those with longstanding chronic conditions, such as diabetes," the authors concluded.
The study is published in the January issue of Archives of General Psychiatry, one of the JAMA/Archives journals.