More than 10 percent of U.S. adults (23.5 million) have diabetes, while major depression affects about 14.8 million adults every year. According to the study’s authors: "Although it has been hypothesized that the diabetes-depression relation is bidirectional, few studies have addressed this hypothesis in a prospective setting.”
After controlling for risk factors such as body mass index (BMI) and physical activity, women with depression were 17 percent more likely to develop diabetes, while those taking antidepressants were 25 percent more likely to develop the disease.
“Our results provide compelling evidence that the diabetes-depression association is bidirectional,” the authors wrote.
Led by An Pan, PhD, Harvard School of Public Health, Boston, the study assessed the relationship between depression and diabetes among 65,381 women aged 50 to 75 years in 1996 and followed up these women for a period of 10 years. During that time span, 2,844 women were diagnosed with type 2 diabetes and 7,415 developed depression.
"The findings from this well-characterized cohort of more than 55,000 U.S. women with 10 years' follow-up add to the growing evidence that depression and diabetes are closely related to each other, and this reciprocal association also depends on the severity or treatment of each condition," the authors wrote.
Although lifestyle factors may have played a role in the association between depression and new cases of diabetes, the association remained significant after adjusting for these factors. Depression therefore may have an effect on risk for diabetes beyond weight and inactivity.
The authors conclude that further research should be done to confirm findings in different populations and investigate the potential mechanisms underlying the association between these two debilitating diseases of the mind and body.
"Furthermore, depression and diabetes are highly prevalent in the middle-aged and elderly population, particularly in women,” the authors wrote. They went on to suggest adequate weight management and regular physical activity as buffers against both conditions.