Individuals with high stress and high hostility levels have an increased risk of developing insulin resistance, which occurs when the body's response to insulin begins to slow down and blood sugar levels begin to rise. People with insulin resistance have a high risk of developing diabetes.

Previous research has shown that insulin resistance is associated with stress and certain personality factors, including hostility. However, the association between hostility and insulin resistance has been inconsistent, Dr. Jianping Zhang explained to Reuters Health.

Zhang, of The Cleveland Clinic, Ohio, and colleagues hypothesized that hostility may interact with stress to affect insulin resistance. To investigate, the team studied 643 men, who were an average of 60.6 years old. The findings are published in the current issue of Psychosomatic Medicine.

The researchers measured the subjects' urine levels of norepinephrine, an indicator of stress, on the assumption that this may be more objective than self-reported levels of stress. The Cook-Medley Hostility scale was used to measure hostility. Insulin resistance was measured by the homeostatic model assessment index, 2-hour post-challenge glucose, and insulin levels after factoring in the influence of nine other risk factors.

"Our study found that there is a statistical interaction between hostility and stress level in predicting insulin resistance," Zhang said. "In other words, people with higher hostility don't always have worse insulin resistance, but they do when they are under stress, especially high levels of chronic stress."

The team also found that not all components of hostility are related to insulin resistance. For instance, cynicism is a personality trait that is strongly related to insulin resistance.

"Because people with high hostility (especially high cynicism) tend to have worse insulin resistance under stress, it is important to target this population for preventive interventions," Zhang said. "Psychotherapy and behavioral interventions may be helpful in reducing stress and physiological arousal, and perhaps prevent insulin resistance in the long run, although so far there is no study testing this yet."

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