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Back: Depression and Diabetes: An Update from the 69th Annual ADA Scientific Sessions

Dr. Richard Rubin Picture

 

Richard R. Rubin, PhD, CDE
PCMG Steering Committee Member

Presentations at the recent ADA meetings in New Orleans contribute to our understanding of the association between depression and bad diabetes outcomes. We learned that people who have diabetes are 1.5 to 2 times more likely to be depressed than people in the general population, and that depression in people with diabetes is associated with higher blood glucose levels, higher complication and mortality rates, and higher health care costs.

Interest in the association between depression and diabetes actually began a long time ago. In 1674, Thomas Willis, the famous British physician who identified glycosuria as a sign of diabetes, wrote that diabetes was caused by “sadness or long sorrow and other depressions”.  For almost 300 years no one pursued Willis’ provocative hypothesis, but just over a decade ago research interest in Willis’ original idea was renewed, with fascinating results. These studies suggest that when it comes to type 2 diabetes, Willis was on to something. In fact, a meta-analysis published last year and widely discussed in New Orleans, suggests that having depression increases a person’s risk of developing type 2 diabetes by about 60%.

How could depression increase diabetes risk?

Behavioral mechanisms
Depression is associated with a wide range of behaviors that are known diabetes risk factors, including physical inactivity, higher BMI, smoking, and sleep disturbances. Several large randomized clinical trials (including the Diabetes Prevention Program [DPP] in which I am an investigator) have shown that losing as little as 10 pounds can reduce the risk of developing type 2 diabetes by over 50% in those at high risk.

Psychoneurohormonal mechanisms
Depression could also increase diabetes risk via psychoneurohormonal mechanisms, and studies on many of these mechanisms were presented in New Orleans. Depression can be seen as a stress response gone awry. Stress triggers release of catecholamines, growth hormone, glucagon, and cortisol, all of which increase blood glucose levels. When a person is depressed, this release is abnormally prolonged. Depression is also associated with hypersecretion of proinflammatory cytokines, which may not only increase diabetes risk by interfering with insulin action, but also contribute to the risk of cardiovascular disease, the leading cause of death in people with diabetes. 

Antidepressant medication use and diabetes and cardiovascular risk
I was first author of a paper published last year showing that DPP participants in the lifestyle and placebo arms of the study were 2-3 times as likely to develop diabetes during the study if they were taking antidepressants than if they were not, and that this elevated risk remained when we controlled for every other diabetes risk factor, including weight and depression symptoms. This was the first study to look at this association. It could be that the people taking antidepressants had been more severely depressed in the past (they were not depressed during the DPP) and that this past depression raised their risk of developing diabetes, or it might be that antidepressants have an effect on diabetes risk.

In New Orleans I presented related data from the Look AHEAD study, a large long-term study of the health benefits of weight loss in people who already have type 2 diabetes. My presentation showed that on entry to the study participants were much more likely to have elevated cardiovascular risk (as assessed by blood glucose, blood pressure, and lipid levels or taking medication to control these levels, along with BMI >30 and smoking) if they were taking antidepressants than if they were not. 

At ADA meetings in the future we are sure to see the results of new studies of the time course of comorbid depression and diabetes, and of the possible effects of antidepressant medication on diabetes and CVD risk. I look forward to sharing these results with you.

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