Taking antidepressants seems to dramatically increase the risk of developing type 2 diabetes among people who are already at risk for the disease.

That is the finding from a major government-funded study designed to determine the role of lifestyle and drug therapy in preventing diabetes.

Researchers from the Diabetes Prevention Program, sponsored by the National Institutes of Health, reported that depression alone did not predict progression to diabetes in people at risk for the disease. But taking antidepressants was associated with a two- to threefold increase in risk.

The increase was not seen, however, in people at high risk for diabetes who were taking both antidepressants and the blood-sugar-regulating drug glucophage (metformin).

The findings were reported at the American Diabetes Association’s 66th Annual Scientific Session, held in Washington.

Antidepressants and Diabetes

While some antipsychotic drugs are known to raise diabetes risk, the new research is the first to find that antidepressant drugs may also increase risk.

“We have to keep in mind that this occurred in a population at very high risk for diabetes so we don’t know whether the findings would apply to the general population, but this should be explored further,” says American Diabetes Association president Richard R. Rubin, PhD.

While the stresses and health problems that accompany diabetes can certainly bring on depression, there is also some suggestion that the metabolic factors that drive diabetes also play a role in diabetes.

Depression's Role in Diabetes

Several other studies presented at the ADA meeting addressed the chicken and egg issue of whether depression causes diabetes or vice versa.

In one such study, researchers from Emory University School of Medicine in Atlanta examined blood sugar control, or glucose tolerance, of 443 healthy adults without known diabetes or glucose intolerance who were and were not being treated for depression. Glucose intolerance is the major indicator of diabetes.

The researchers thought they would find that depressed patients had higher levels of prediabetes and undiagnosed diabetes disease than people who were not depressed, but this is not what they found.

After adjusting for diabetes risk factors such as weight, age, and race, little association was seen between depression and glucose intolerance. Although diabetes was associated with depression, unrecognized glucose intolerance was not.

“Since these results suggested that awareness of the health risks conferred by diabetes may contribute to depression, patients with newly diagnosed glucose intolerance should be counseled appropriately and monitored for development of depression, researcher Lawrence S. Phillips, MD, and colleagues wrote.

Role of Hormonal Changes

But other research suggests that depression predisposes people to diabetes. In a presentation at the ADA meeting Johns Hopkins School of Medicine epidemiology professor Sherita Hill Golden, MD, suggested that hormonal changes seen with depression could also cause diabetes.

Specifically, the stress hormones adrenaline and cortisol could be the culprits, she tells WebMD.

“Both of these hormones are increased in people who have depression, and we also know that these two stress hormones also alter glucose metabolism as well,” she says.

Stress hormones are also thought to play a role in cardiovascular risk.

If the theory is correct, then medications being developed to keep these hormones in check may prove to be effective diabetes and heart-disease-prevention drugs, she says.

By Salynn Boyles, reviewed by Louise Chang, MD

SOURCES: American Diabetes Association 66th Annual Scientific Sessions, Washington, June 9-13, 2006. Richard R. Rubin, PhD, president, American Diabetes Association; associate professor, medicine and pediatrics, Johns Hopkins University School of Medicine, Baltimore. Sherita Hill Golden, MD, assistant professor of medicine and epidemiology, Johns Hopkins University School of Medicine. National Institute of Mental Health: “Depression and Diabetes.” Lawrence S. Phillips, MD, professor of medicine, division of endocrinology and metabolism, Emory University School of Medicine, Atlanta.