The prevalence of diabetes increases with age, with a 25.2% prevalence in those aged 65 years or older. Type 2 diabetes is the most common type, accounting for 90% to 95% of all diagnosed cases in adults. Obesity, a family history of diabetes, race/ethnicity, and physical inactivity are major risk factors for diabetes. But these are not the only determinants.

Accumulating evidence supports the fact that depression and cynicism also are associated with an increased risk of diabetes. In addition, high levels of hostility have been associated with high fasting glucose levels, insulin resistance, and prevalent diabetes. Few studies, however, have investigated the association of potentially protective personality characteristics with diabetes risk.

The objective of this study was to examine whether personality traits, including optimism, negativity, and hostility, were associated with the risk of developing type 2 diabetes in postmenopausal women. The study went on to explore whether the association could be mediated by behavioural pathways, such as diet, physical activity, smoking, or high alcohol consumption.

The study followed 139,924 postmenopausal women from the WHI who were without diabetes at baseline. During 14 years of follow-up, 19,240 cases of type 2 diabetes were identified. Compared with women in the lowest quartile of optimism (least optimistic), women in the highest quartile (most optimistic) had a 12% lower risk of incident diabetes. Compared with women in the lowest quartile for negative emotional expressiveness or hostility, women in the highest quartile had a 9% and 17% higher risk of diabetes, respectively. The association of hostility with the risk of diabetes was stronger in women who were not obese compared with women who were.

As a result of these outcomes, the study concluded that low optimism, high negativity, and hostility were associated with increased risk of incident diabetes in postmenopausal women, independent of major health behaviours and depressive symptoms.

"Personality traits remain stable across one's lifetime; therefore, women at higher risk for diabetes who have low optimism, high negativity, and hostility could have prevention strategies tailored to their personality types," says Dr JoAnn Pinkerton, NAMS executive director. "In addition to using personality traits to help us identify women at higher risk for developing diabetes, more individualized education and treatment strategies also should be used."