Depression linked to higher mortality risk in non-insulin treated type 2 diabetes

A Norwegian study reports that elevated symptoms of depression are associated with a greater mortality risk in people with type 2 diabetes who do not use insulin.
A total of 948 participants were studied in the research, all of whom had been part of the Nord-Trøndelag Health Survey conducted during 1995–97, and completed questionnaires with subscales of anxiety and depression.
All the participants, who had type 2 diabetes and did not use insulin, were followed for 17 years or until death.
At the beginning of the study, the researchers examined associations between elevated anxiety symptoms, depressive symptoms and mortality. These factors were then adjusted for health markers such as HbA1c, cardiovascular disease and sociodemographic factors.
After a mean follow-up of 12 years, 57 per cent of the participants had died. Those with elevated depression symptoms alone were found to have an increased mortality risk.
“The finding that depression is associated with increased mortality rates is in line with results of a meta-analysis which showed that depression was associated with a 46% higher mortality rate in persons with diabetes,” said the study authors.
But patients who had elevated symptoms in both anxiety and depression did not have an increased mortality risk, while those with elevated anxiety symptoms actually had a decreased mortality risk and lower HbA1c levels.
The researchers noted the decrease in this group was “in part explained by lower HbA1c levels. This may be interpreted as lending weight to a hypothesis of elevated levels of anxiety symptoms leading to behaviour that counteract the adverse health effects of type 2 diabetes.
“The hypothesis that elevated levels of anxiety symptoms leads to behaviour that counteracts the adverse health effects of type 2 diabetes needs further investigatio,” said the researchers.
The findings appear in the online journal PLOS ONE.