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Study affirms connection between diabetes, depression

Key factors in keeping diabetes under control is being active, keeping weight down, and eating properly, but for someone with depression, these tasks might seem impossible.

According to the American Diabetes Association (ADA), between one and three of every 10 people with diabetes has depression, and research has affirmed the connection. “Examining a Bidirectional Association Between Depressive Symptoms and Diabetes,” published in the June 18 Journal of American Medical Association, found that those with elevated depressive symptoms had a modest increased risk of developing type 2 diabetes, regardless of sociodemographics and metabolic factors.

The study also found that without elevated symptoms at baseline, “treated type 2 diabetes was associated with a significantly higher odds of developing depressive symptoms during follow-up, independent of [body mass index], socioeconomic status, and comorbidities.”

Sherita Hill Golden, MD, MHS, associate professor of medicine and epidemiology and director of inpatient diabetes management service at Johns Hopkins University School of Medicine in Baltimore and coauthor of the study, says healthcare should recognize that diabetes and depression are comorbid conditions and treatment programs are needed for both issues.

The connection might not be from the physical symptoms of diabetes, but the burden of caring for the disease.

“We hypothesize that the reason that treated diabetes, and not untreated diabetes or prediabetes, [is] associated with a higher risk of depression is that treatment for diabetes is associated with more monitoring, requires more medication adherence, and may be a marker of more severe disease with complications. This disease burden may lead to depression,” says Golden.

The study authors note the association between the two diseases and link the “psychological stress associated with diabetes management.” In addition, adults with treated type 2 diabetes may have comorbidities that could lead to more depressive symptoms.

The study, which the authors said was the first “population-based study to show a bidirectional longitudinal association between type 2 diabetes and elevated depressive symptoms within the same cohort,” concluded that a “modest association of baseline depressive symptoms with incident type 2 diabetes existed that was partially explained by lifestyle factors.” The study authors said the results corroborate previous findings that show that depressed patients “have higher calorie intake, are less physically active, and are more likely to be smokers.”

One possible explanation the study authors noted for the diabetes-depression connection is that “depressive symptoms are associated with several metabolic and behavioral risk factors for type 2 diabetes. First, 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.”

They say the findings suggest that clinicians should understand the increased risk of elevated depressive symptoms in those with treated type 2 diabetes. They add that healthcare providers should consider routine screening for depressive symptoms among these patients.

Golden says physicians and mental health professionals must educate patients on both diseases and remove the stigma associated with treatments for depression.

“Physicians who take care of patients with diabetes should conduct depression screening, as the presence of high depressive symptoms may impair the patient’s ability to care for his/her diabetes,” says Golden.

Mental health providers should also understand the connection. “Psychiatrists/psychologists/social workers should be aware that depression can be a risk factor for type 2 diabetes, are more likely to engage in unhealthy behaviors (overeating, not exercising) and as a consequence are more likely to be obese. They should encourage their overweight patients to be screened for diabetes by their primary medical doctors,” Golden wrote in an e-mail.

Golden says she is hopeful that the study’s publication and other research in the diabetes-depression space will raise awareness of the diabetes-depression connection. “Many practitioners recognize that [the diseases] are linked, but depending on their subspecialty, they may be more likely to focus on one more than the other without recognizing that they are linked,” she says.

John B. Buse, MD, PhD, president of medicine and science at the ADA, says the diabetes-depression connection is well established. There is plenty of debate as to why the connection is present. “The thing that is unclear is whether it’s just a two-way street or whether they sort of share a common route system,” says Buse, who believes there is a biological connection. “There is a lot about the relationship that we don’t understand, but it does seem very clear that the relationship exists.”

Buse says the ADA recommends that physicians screen diabetes patients for depression. He adds that some health systems use screening questionnaires to identify people who are experiencing mental illness.

Most PCPs know about the connection between depression and diabetes, Buse adds, but the mental health professional side of care is more of a problem. This is partly because most psychologists’ offices don’t have nurses or equipment to medically test patients.

“It is something that needs to be addressed in the mental health system either by creating mechanisms that make sure problems are addressed by the primary care physician or setting up a system within the mental health system,” says Buse.

Study specifics

The authors of “Examining a Bidirectional Association Between Depressive Symptoms and Diabetes,” published in the June 18 Journal of American Medical Association, used repeated measures of fasting blood glucose and depressive symptoms over time to see whether depression predicted type 2 diabetes and whether those with type 2 diabetes at baseline were more likely to develop more severe depressive symptoms.

Unlike prior studies that examined the connection solely in the elderly population, the study authors opened it up to a wider age range. Between July 2000 and August 2002, the study authors recruited 6,814 men and women aged 45–84 who identified themselves as white, black, Hispanic, or Chinese and who were free of self-reported clinical cardiovascular disease. Those involved in the study came from the following communities: Baltimore City and Baltimore County; Chicago; Forsyth County, NC; Los Angeles; Northern Manhattan and the Bronx, NY; and St. Paul, MN.

To test for depression, the patients were assessed during the first and third doctor visits using the CES-D, a 20-item questionnaire to assess depression. The questions gauge depressed mood, feelings of worthlessness, feelings of hopelessness, loss of appetite, poor concentration, and sleep disturbance.

In addition to the depression evaluations, physicians checked the patients for impaired fasting glucose and type 2 diabetes status. Those with impaired fasting glucose and type 2 diabetes were more likely to be older, male, nonwhite, less physically active, and suffer from a higher body mass index, according to the study.

Additionally, those with untreated type 2 diabetes attained a lower educational level, had a lower annual income level, were more likely to have microalbuminuria and hypertension, and had lower high-density lipoprotein cholesterol and higher triglycerides.