Link Seen Between Mental Disorders, Diabetes in New Study

In a large international study, researchers found an association among binge-eating disorder, bulimia nervosa, depression, and intermittent explosive disorder and the later occurrence of type-2 diabetes.

The study was headed by Peter de Jonge, Ph.D., a professor of psychiatry at the University of Groningen in the Netherlands, who along with colleagues conducted face-to-face household surveys of some 52,000 community-dwelling adults in 19 countries. Most of the surveys were based on nationally representative household samples, except for those from Colombia, Mexico, and China, which were based on representative household samples in urban areas.

The results are published in the April Diabetologia, the journal of the European Association for the Study of Diabetes.

The World Health Organization Composite International Diagnostic Interview was used to retrospectively evaluate the lifetime prevalence and age at onset of 16 DSM-IV psychiatric disorders, including several anxiety disorders, mood disorders, impulse control disorders, and substance use disorders. Anorexia nervosa was excluded because there was too low a prevalence of it in the study population to produce reliable analyses.

Subjects were also asked whether their physicians had diagnosed them for type-2 diabetes, and if so, when the diagnosis occurred.

The researchers then looked to see whether they could find any significant links between the mental disorders of interest and subjects’ subsequent diagnosis of type-2 diabetes, while taking comorbidity of the various mental disorders into account.

Their data did point to links between diabetes and four mental disorders—binge-eating disorder, bulimia nervosa, major depressive disorder, and intermittent explosive disorder. The odds ratio for developing diabetes was especially high for individuals with binge-eating disorder or bulimia—3 to 1 in the case of the former and 2 to 1 in the case of the latter.

“These findings support the focus on depression as having a role in diabetes onset, but suggest that this focus may be extended towards impulse-control disorders,” the researchers said.

They suggested that the association between binge eating and diabetes and between bulimia and diabetes “point to the importance of glucose dysregulation. . .which may eventually result in later diabetes.” As for the link they found between intermittent explosive disorder and later development of diabetes, it’s possible that it might be explained by “low levels of HDL cholesterol and decreased serotonin functioning, both of which have been associated with aggression and diabetes.”

The findings also have clinical implications, the researchers pointed out. For example, if depression is indeed a risk factor for type-2 diabetes, and if it is successfully treated, could such treatment decrease the chances of people developing type-2 diabetes? “This is theoretically plausible, since the typical age of onset of depression is considerably lower than the typical age of diabetes onset,” they noted.

Also, the lifetime rate of major depressive disorder in individuals with eating disorders has been found to be as high as 50 percent to 75 percent, they said. It thus “remains possible for a person to develop an eating disorder, become depressed later on, and in the end develop diabetes. Targeting the eating disorder in this case will theoretically be a far more promising approach [to preventing diabetes] than focusing solely on depression.”

“Perhaps further studies could evaluate the possibility that impulse-control disorders, including eating disorders and intermittent-explosive disorder, may serve as risk factors for depression and diabetes, or that these disorders are expressions of an underlying pathology that might lead to diabetes.”

“Although affective disorders are well known to be associated with diabetes, this international epidemiological study finds an association between glucose dysregulation and a variety of other psychiatric disorders as well,” psychiatrist Thomas Wise, M.D., medical director of Inova Health Systems in Falls Church, Va., and a psychosomatic medicine expert, said in an interview with Psychiatric News. The research also “reinforces the urgent need to develop practical models of psychiatric integration into primary and specialty care settings to work as part of a team utilizing disease and behavioral approaches for such serious comorbid disorders.”

The study was funded by the National Institute of Mental Health, the John D. and Catherine T. MacArthur Foundation, the Pfizer Foundation, multiple international organizations, and several pharmaceutical companies. ■

An abstract of “Association Between DSM-IV Mental Disorders and Diabetes Mellitus: A Role for Impulse Control Disorders and Depression” can be accessed here.