Stress of Dealing with Diabetes Linked to Depression

By John Gever
BALTIMORE, 18 june 2008-- Type 2 diabetes and depression appear intertwined.
Patients with type 2 diabetes were more likely to develop depression and vice-versa, suggested a five-center study reported by Sherita Hill Golden, M.D., of Johns Hopkins, and colleagues in the June 18 issue of the Journal of the American Medical Association.
In parallel studies of participants in the Multi-Ethnic Study of Atherosclerosis, they found that patients under treatment for type 2 diabetes, but not those with untreated disease of comparable severity, were at a significantly increased risk for developing depressive symptoms over the next few years.
They suggested that the worries and burdens of managing their diabetes may lead to depression. "The psychological stress associated with diabetes management may lead to elevated depressive symptoms," they wrote.
At the same time, the investigators found a nonsignificant trend for depressed patients to develop type 2 diabetes, primarily because of lifestyle changes engendered by depression.
They concluded that the studies support a "bidirectional association" between depression and type 2 diabetes, in which each contributes to or exacerbates the other.
Patients with type 2 diabetes had an odds ratio of 1.54 (95% CI 1.13 to 2.09) of developing depressive symptoms during three to four years of follow-up, compared with participants with normal glucose, the researchers found.
However, among those with fasting plasma glucose levels indicative of type 2 diabetes but who were not under treatment, the odds ratio for developing depressive symptoms was 0.75 (95% CI 0.44 to 1.27).
They recommended that clinicians consider screening their patients with type 2 diabetes for depressive symptoms.
The Multi-Ethnic Study of Atherosclerosis was a longitudinal cohort study in which 6,814 people underwent a comprehensive health and lifestyle assessment from 2000 to 2002, and were then followed until 2004 and 2005. In the two parallel analyses, the numbers of participants add up to more than 6,814 because those without depressive symptoms or diabetes at baseline were included in both analyses.
In one analysis, the researchers selected 5,201 persons without diagnosed type 2 diabetes at baseline, and grouped them according to the presence or absence of depressive symptoms. The subsequent development of type 2 diabetes was determined for each group.
The other study, involving 4,847 participants, was structured similarly but focused on development of depression among patients without depressive symptoms at baseline, stratified by type 2 diabetes diagnosis.
The researchers grouped the patients without depression at baseline according to the presence or absence of type 2 diabetes. The subsequent development of depressive symptoms was determined for each group.
In the first study, the researchers found that only diagnosed and treated type 2 diabetes predicted development of depressive symptoms.
Elevated fasting plasma glucose at baseline actually appeared to be somewhat protective (HR 0.79, 95% CI 0.63 to 0.99), a finding Dr. Golden and colleagues could not explain. They called for more studies to confirm the relationship and identify likely mechanisms.
Adjusting for diabetes severity, comorbidities, and lifestyle factors including diet did not much influence the relationships between diabetes status and subsequent depression, the researchers said.
For example, the positive association between treated type 2 diabetes and subsequent depressive symptoms shrank only slightly in the fully adjusted model, to an odds ratio of 1.52 (95% CI 1.09 to 2.12).
Dr. Golden and colleagues found in the second study that for each five-point increase in scores on the Center for Epidemiologic Studies Depression Scale at baseline, the risk of developing diabetes increased by 10% (95% CI 2% to 19%) after adjusting for demographic factors and body mass index.
However, the relationship became statistically insignificant when the adjustment included lifestyle factors such as diet and smoking (HR 1.08 per five-point increase in depression scores, 95% CI 0.99 to 1.19).
The researchers said depression may still contribute to development of type 2 diabetes despite this lack of significance in the adjusted model.
"Depressed individuals are less likely to comply with dietary and weight loss recommendations and more likely to be physically inactive, contributing to obesity, a strong risk factor," Dr. Golden and colleagues pointed out.
"Future studies should determine whether interventions aimed at modifying behavioral factors associated with depression will complement current type 2 diabetes prevention strategies," the researchers said.
They noted that their data were scant in some respects. The depression scale they used was not designed to measure clinical depression, and the study had only one follow-up assessment of depressive symptoms. The study also did not collect detailed information on diabetic complications or disease severity.
The study was funded by the National Institutes of Health.
Study authors reported relationships with Merck, Novo Nordisk, Associated Jewish Federation of Baltimore, the Weinberg Foundation, Forest, GlaxoSmithKline, Eisai, Pfizer, AstraZeneca, Lilly, Ortho-McNeil, Bristol-Myers, Novartis, Supernus, Adlyfe, Takeda, Wyeth, Lundbeck, Merz, and Health Monitor.
Primary source: Journal of the American Medical AssociationSource reference:Golden S, et al "Examining a bidirectional association between depressive symptoms and diabetes" JAMA 2008; 299: 2751-59.