Estimating the relative Treatment effect for comorbid Depression in People with Diabetes Mellitus

Diabetes Mellitus is a long-term condition affecting around 1 in 11 adults worldwide, which can result in serious complications requiring extensive health care treatment. Around one third of diabetes patients also have depression.

Research shows that people with diabetes (either type 1 or type 2) can have an increased risk of developing depression, and people with depression have a greater chance of developing type 2 diabetes. Although the relationship between diabetes and depression is not fully understood, the conditions are thought to be linked in a number of ways. For example, the stress associated with managing diabetes and associated complications can lead to an increase in depressive symptoms. Conversely, depression often leads to poor health behaviours such as unhealthy diets, physical inactivity, smoking and alcohol use, all of which are risk factors for diabetes. Depression can also interfere with people’s ability to manage their condition.

Compared to patients without depression, people with diabetes and depression often suffer from more diabetes symptoms. They have trouble controlling their blood sugar, and are more likely to develop complications. They also have higher death rates. Therefore, gauging appropriate and successful treatments for this comorbidity is both a health and an economic priority.

A systematic review conducted in 2010 by members of the research group found there are a number of effective treatments for people with diabetes and depression, shown to improve depressive feelings and in some cases blood glucose levels. These included medications for both diabetes and depression, psychotherapy (mainly cognitive behavioural therapy), and collaborative care in which treatment is supervised by a nurse case manager that steps up therapy when required. However, the effects on diabetes outcomes were more limited than the effects on depression outcomes. As treatments are likely to have developed considerably over the past ten years, our research group updated the review to determine the effect size of these treatments for improving both diabetes and depression outcomes.