The study, conducted by scientists at University College London (UCL) and the University of Zurich, also found that people with type 2 diabetes are physically less able to recover from stress than people without diabetes.
In the study, published in Proceedings of the National Academy of Sciences, the researchers compared 420 adults, ranging in age from 50 to 75 years old. Subjects with and without diabetes were matched by age, gender, and income. Study participants completed standard questionnaires to measure their psychological stress. They also underwent laboratory tests to measure biological responses to mental stress tests.
People with Diabetes Have Higher Levels of Cortisol
The participants with type 2 diabetes were less able to bring their blood pressure, heart rate, and cholesterol levels back down to normal after a stressful experience. They also had higher levels of the stress hormone cortisol in their blood and higher levels of IL-6, a protein involved in the immune system response.
These two factors combined could lead to increased strain on the body as it tries to maintain a stable internal environment, according to the researchers.
Although the study shows a link between the biological processes involved in stress and type 2 diabetes, the results do not show that extra strain on the body from stress is either a cause or a consequence of type 2 diabetes, according to the researchers. Instead, the results show the need for treatments that target both the psychological and physical effects of chronic illness.
Diabetes Patients at High Risk for Psychological Stress
Lead researcher Andrew Steptoe, a professor of psychology at the British Heart Foundation and director of the Institute of Epidemiology and Health Care at UCL, told Healthline, “What we found is that people with type 2 diabetes were at higher risk than the matched set of non-diabetic participants for psychological stress. They experienced more chronic stress exposure in terms of money concerns and neighborhood problems, were more depressed, more pessimistic about the future, and reported a lower sense of control over their lives.”
Steptoe said researchers found the patients' biological responses to stress “particularly interesting."
"Everybody shows increases in blood pressure, pulse rate, and certain hormones when they are confronted by stressful situations; this is a natural process," he said. "The healthy profile is to show a brisk mobilization of these biological responses followed by a rapid return to resting levels once the challenge is over."
But, Steptoe said, people with type 2 diabetes showed a different response. "Their blood pressure, heart rate, and cholesterol responses to stress were blunted, indicating they were unable to mobilize these processes to an optimal extent," he said.
The type 2 diabetes patients' recovery rate was slower, suggesting that their bodies were unable to rein in their response to stress, explained Steptoe.
What Do Outside Experts Say?
Dr. Gerald Bernstein, director of the diabetes management program at the Friedman Diabetes Institute at Mount Sinai Beth Israel in New York, believes Steptoe's findings are important.
Bernstein told Healthline, “All of us respond to stress with the same mechanisms — lots of cortisol, and other factors. This allows us to tolerate the stress and do what we need to do. If that mechanism is impaired, the response is less than ideal. If blood glucose is chronically elevated, it interferes with normal reactions, so people with type 2 diabetes will not respond in the best way."
Bernstein pointed to a 1998 study, "Valuing Quality of Life and Improvements in Glycemic Control in People with Type 2 Diabetes," saying it showed that modest elevations in blood sugar levels can interfere with quality of life at home and in the workplace. "I think this study shows us why," he said.
Dr. Sandra T. Foo, an assistant professor of medicine, endocrinology, diabetes, and bone disease at the Icahn School of Medicine at Mount Sinai, told Healthline, “Dr. Steptoe proposes that prolonged 'life stress' (allostatic load) can potentially be a cause of type 2 diabetes. This is a theory that may have some physiological basis, but is a challenging one to prove. Diabetes risk can be linked to multiple factors such as genetics, body weight, and lifestyle. In clinical practice, we know that high levels of stress can have a strong effect on diabetes control."
Foo went on to say that although diabetic patients may have higher stress hormone levels and a more "inflammation markers” in their blood, it is hard to prove that stress is the cause of type 2 diabetes. "It may be a situation of the chicken versus the egg," she said. "Did stress lead to diabetes? Or did developing diabetes lead to more stress in their lives? Can stress itself lead to diabetes without other risk factors?"
Donna Ryan, RN, CDE, manager of patient education programs on diabetes, smoking cessation, and asthma at Sacred Heart Hospital in Pensacola, Florida, told Healthline, "The study provides further evidence that patients with diabetes have biological differences to stress, and emphasizes the importance of treatment, referral, and patient education for stress reduction."
Ryan added that further studies are needed to help determine which stress reduction techniques have a positive impact on allostatic load, or wear and tear on the body, in patients with diabetes.