Positive Thinking Shows Power in Preventing Diabetes

Nancy A. Melville

January 31, 2019

Stress and negativity are known risk factors for a host of adverse health effects; however, new research indicates that a glass-half-full approach is also powerful in independently reducing the risk of type 2 diabetes, at least in postmenopausal women.

"Ours is the first study to report that optimism is related to lower risk of diabetes," first author Juhua Luo, PhD, School of Public Health, Indiana University, Bloomington, told Medscape Medical News.

"Associations were independent of major health behaviors and depressive symptoms, suggesting that women's personality traits may also be considered in prevention of diabetes in addition to promotion of healthy behaviors," Luo added.

Depression, along with obesity, family history, and race/ethnicity, are known risk factors for type 2 diabetes, but research is lacking on a potential role of other psychological factors, including optimism.

Analyzing WHI Data for Links Between Behaviors and Diabetes

In the new analysis, published online January 21 in Menopause, Luo and colleagues evaluated data on 139,924 postmenopausal women aged 50 to 79 years from the Women's Health Initiative (WHI) who did not have diabetes at baseline when enrolled in the trial between 1993 and 1998.

Over a mean follow-up of 14 years (range, 0.1 to 23 years), 19,240 of the women developed type 2 diabetes, as assessed by self-report or physician-diagnosed diabetes.

Personality traits were evaluated using questionnaires as part of the trial. Results of the Life Orientation Test showed that women in the highest quartile of optimism had a 12% lower risk of incident diabetes compared with those in the lowest quartile of optimism (hazard ratio [HR], 0.88; 95% CI, 0.84 - 0.92).

Negativity also affected the risk, in this case increasing it: those in the highest quartile of negative emotional expressiveness, measured using four items on the Emotional Expressiveness Questionnaire, had a 9% greater risk of diabetes (HR, 1.09).

And hostility, assessed using the cynical subscale of the Cook and Medley questionnaire, was associated with as much as a 17% higher risk of diabetes (HR, 1.17), compared with those in the lowest respective quartiles.

Interestingly, the association between hostility and diabetes was stronger in people who were not obese compared with those who were (P = .02).

"It is possible that factors related to emotions are overshadowed by obesity-related mechanisms in obese women," the authors speculate.

In general, personality traits can be assumed to play a role in the risk of diabetes by influencing everything from poor diet to physical activity or alcohol consumption, they say.

But importantly, the associations between diabetes and optimism, hostility, and negative emotional expressiveness were seen even after adjusting for many potential confounders, including depression.

"If you [have]...two people with a poor diet but one is optimistic and the other not, the optimistic person will still have a lower risk," Luo said.

"That being said, diet is itself still a powerful influence, so we are not saying people can ignore their diets."

Stress/Cortisol a Possible Biological Mechanism?

Luo and colleagues suggest that stress and one of its associated hormones, cortisol, may play a role in explaining their findings.

"There is some evidence showing that a rise in the concentration of proinflammatory cytokines and glucocorticoids, particularly cortisol, is present in conditions of chronic stress and often in depression, which may lead to accumulation of visceral fat or lipolysis or release of free fatty acids and then insulin resistance."

They note that the results support previous studies linking positive psychological traits to improved glucose control and lower mortality rates in type 2 diabetes.

In addition, two other studies have found a link between angry temperament and the onset of diabetes. And a prior report showed a link between long-term stress, measured according to cortisol in hair samples of more than 2500 men, and obesity, a leading risk factor for type 2 diabetes.

Awareness May Help Clinicians, Patients

In terms of clinical implications, the challenge of brightening a patient's outlook may be much easier said than done, says Luo, but clinicians and patients alike may nevertheless benefit from knowing about this link.

"Personality traits are difficult to change, especially among older persons," Luo explained.

"However, perhaps we can use information about personality to guide clinical or programmatic intervention strategies. For example, a person with low levels of optimism may be encouraged to set modest initial goals to encourage success."

The authors have reported no relevant financial relationships.

Menopause. Published online January 21, 2019. Abstract

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