Depression may boost risk of type 2 diabetes

The findings showed that people who suffer with depression and metabolic risk factors such as obesity, high blood pressure and unhealthy cholesterol levels are more than six times more likely to develop type 2 diabetes.

People with depression, alone, were not at significantly greater risk of developing type 2 diabetes.

But people only with metabolic risk factors like obesity, high blood pressure and unhealthy cholesterol levels and not depression were around four times more likely to develop type 2 diabetes.

"Emerging evidence suggests that not depression, per se, but depression in combination with behavioural and metabolic risk factors increases the risk of developing type 2 diabetes and cardiovascular conditions," said lead author Norbert Schmitz, associate professor in McGill University in Canada.

The results, published in the journal Molecular Psychiatry, suggested that when depression combines with metabolic risk factors the risk of developing diabetes rises to a level beyond the sum of its parts.

For the study, the researchers analysed 2,525 participants who were aged between 40 and 69 for four-and-a-half year. 

They divided them into four groups: those with both depression and three or more metabolic risk factors; two groups, each with one of these conditions but not the other; and a reference group with neither condition.

The study indicated that depression, metabolic symptoms and the risk of developing diabetes interact in a number of ways and in some cases depression and metabolic risk factors may aggravating one another.

The researchers emphasised that not all cases of depression are the same - only some people with depression also suffer from metabolic problems.

"Focussing on depression alone might not change lifestyle/metabolic factors, so people are still at an increased risk of developing poor health outcomes, which in turn increases the risk of developing recurrent depression," Schmitz suggested.