Studies have shown that psychosocial stress contributes to the development of type 2 diabetes and makes it more difficult for people who have the disease to manage their blood sugar. But what's behind that connection, and does being overweight influence the role of stress in the development of the disease?

Cardiology researchers at Massachusetts General Hospital set out to find the answer to these questions by observing amygdalar activity—the metabolic activity in a region of the brain called the amygdala, which is known to be activated by stress. The research was led by Michael T. Osborne, MD, an assistant in medicine in the Corrigan Minehan Heart Center, and Ahmed A. Tawakol, MD, co-director of the Cardiac MR PET CT Program.

The Link Between Stress and Diabetes

The researchers looked at the amygdalar activity of 232 people who underwent advanced brain imaging at Mass General between 2005 and 2008 but who did not have diabetes at the time. They measured the patients' amygdalar activity using an advanced imaging technique called 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT). The technology was also used to measure the patients' visceral adipose tissue (VAT), which is the fat that can build up in the abdomen and raise the risk of developing type 2 diabetes.

When they examined the results, the link between stress and diabetes risk was clear. Those with high amygdalar activity had a fivefold increased risk of developing type 2 diabetes regardless of their body weight. But those who were both stressed and overweight faced the greatest risk.

The findings underscore the importance of considering stress when physicians are screening patients for diabetes risk. Once physicians identify patients who are at high risk of diabetes because of stress, they can take proactive steps to help prevent the disease from developing, such as recommending stress management and mindfulness-based stress reduction interventions.

A Two-hit Risk for Diabetes

Examining how body weight affects diabetes risk in the context of stress is important because being overweight or obese is known to raise the risk of developing the disease. The Mass General team slotted each patient they studied into one of four groups:

  • Low body weight and low stress (as measured by amygdalar activity)
  • Low body weight and high stress
  • High body weight and low stress
  • High body weight and high stress

In every scenario, low amygdalar activity translated to a low risk of developing type 2 diabetes, even among overweight people. As evidence of stress increased, so did diabetes risk. However, the patients with both high amygdalar activity and high body weight faced the greatest risk of developing the disease. What's more, increases in amygdalar activity raised the risk of diabetes independently of changes in body weight that occurred over time.

The findings suggest that amygdalar activity and obesity act synergistically to increase the risk of developing type 2 diabetes. The study referred to the combination of stress and high body weight as a "two-hit" mechanism that promotes the development of the disease. Researchers even observed a link between amygdalar activity and signs of inflammation and metabolic impairment—both of which are risk factors for diabetes.

Then they analyzed the patients three times using different measures of body weight: body mass index (BMI), baseline VAT and the change in VAT.

Managing Stress to Lower Diabetes Risk

The authors wrote that they gained important knowledge thanks to the unique hybrid imaging they used, which allowed them to simultaneously measure body weight and amygdalar activity. These insights can now be used by doctors to better help patients manage and lower their risk of developing type 2 diabetes.