People who have depression in addition to well-established risk factors for type 2 diabetes, such as obesity, hypertension, and unhealthy cholesterol levels, may be even more likely to develop the disease than if they had these metabolic risk factors alone, a new study suggests.

Although previous research has demonstrated an association between depression and diabetes, study investigators note that this study adds another dimension to these findings.

“Emerging evidence suggests that not depression, per se, but depression in combination with behavioral and metabolic risk factors increases the risk for developing type 2 diabetes and cardiovascular conditions,” lead study author Norbert Schmitz, PhD, associate professor in the department of psychiatry at McGill University and researcher at the Douglas Mental Health University Institute, said in a press release.

“The aim of our study was to evaluate characteristics of individuals with both depressive symptoms and metabolic risk factors.”

In the study, Dr Schmitz and colleagues included 2525 participants in the Emotional Health and Wellbeing Study in Quebec, Canada, who completed an assessment at baseline and another after 4.5 years of follow up. They were divided into 4 groups: a reference group of participants with no metabolic dysregulation and no depressive symptoms; those with metabolic dysregulation but no depressive symptoms; those with depressive symptoms but no metabolic dysregulation; and those with depressive symptoms and at least 3 metabolic risk factors.

Metabolic risk factors included obesity, elevated blood glucose, hypertension, high triglycerides, and decreased HDL cholesterol.

Of all participants, 3.5% developed diabetes.

Unlike in previous studies, those with depression but no metabolic dysregulation did not have a significantly increased risk for diabetes when compared with the reference group (adjusted OR=1.28; 95% CI, 1.07-2.17).

In contrast, those with metabolic dysregulation only were 4 times more likely to develop diabetes, as compared with the reference group (adjusted OR=4.4; 95% CI, 3.42-5.67).

However, results showed that participants with both depression and metabolic dysregulation had the highest risk for diabetes and were 6 times more likely to develop the condition than the reference group (adjusted odds ratio [OR]=6.61; 95% CI, 4.86-9.01).

Additionally, a structural equation model demonstrated an interaction between depression and metabolic dysregulation, according to the study data.

“Our study highlights the interaction between depressive symptoms and metabolic dysregulation as a risk factor for type 2 diabetes,” the researchers wrote.

Depression and metabolic risk factors may interact in several ways, the researchers noted. For instance, people with depression may be less likely to adhere to medical advice for addressing metabolic risk factors, including eating healthier, quitting smoking, or exercising more often. Moreover, some forms of depression can affect metabolism, leading to weight gain and high blood pressure. Also, some antidepressant medications can cause weight gain.

The researchers cautioned, though, that not all patients with depression have metabolic risk factors, so identifying patients with both problems and tailoring treatment is important.

“Focusing 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,” said Dr Schmitz.

Reference

  1. Schmitz N, Deschênes SS, Burns RJ, et al. Depression and risk of type 2 diabetes: the potential role of metabolic factors. Mol Psychiatry. 2016. doi:10.1038/mp.2016.7.