If you are already at high risk for getting type 2 diabetes, antidepressant drugs can boost that risk, according to new research reported Saturday.
The report was based on a re-analysis of part of the Diabetes Prevention Program, a large-scale study in which researchers reported in 2002 that those at high risk for getting type 2 diabetes who lost excess weight and exercised were able to prevent the onset of diabetes much of the time.
In the new study, to be presented at the annual meeting of the American Diabetes Association (ADA) in Washington, D.C., researchers looked at the effect of antidepressant drugs on a person's proclivity for getting diabetes. They evaluated the effect on those in the three groups studied in the Diabetes Prevention Program: the lifestyle intervention group, the placebo group and the group given the diabetes drug metformin (Glucophage).
Those in the placebo and lifestyle groups who were on antidepressants had a two-to-three times greater risk of getting type 2 diabetes than those from the metformin group taking antidepressants, said Richard Rubin, the lead author and the president-elect of health care and education for the ADA.
"No one has ever looked at whether antidepressant use could increase the risk of adult onset diabetes," said Rubin, who is also associate professor of medicine and pediatrics at the Johns Hopkins University School of Medicine in Baltimore.
For years the debate on whether depression causes diabetes, or vice versa, has been unresolved. But Rubin said this was the first large study to examine the effect of antidepressants on people at high risk of type 2 diabetes.
"We looked at 3,187 participants [in the Diabetes Prevention Program trial] who completed the depression screener," he said. "At the beginning, 5.7 percent were on antidepressants. During the study, about 13.5 percent were taking antidepressants [at least] some of the time."
Some experts think the use of certain types of antidepressants known as SSRIS (such as Prozac and Paxil) could cut the risk of getting diabetes, Rubin said, because some people lose weight on those. But, he added, many experts are finding that the weight loss only occurs soon after the drugs are started, then tapers off or ends.
But taking any kind of antidepressant boosted the risk of getting diabetes, he found. "It didn't matter what antidepressant you were taking (tricyclic antidepressant or SSRI), the risk of getting diabetes was still there in the placebo or lifestyle arm," he said.
Why this effect occurs and why metformin seems to protect against it is not known, Rubin added.
In the analysis, he ruled out whether those who developed diabetes did so because of weight gain alone, less physical activity or increased insulin resistance, all of which boost the risk of getting type 2 diabetes.
The findings could have enormous public health implications, Rubin said. "Forty million people in the United States are pre-diabetic," he said, referring to a condition in which blood glucose levels are rising, putting the person at risk of developing type 2 diabetes. According to the U.S. government's National Diabetes Information Clearinghouse, almost 21 million Americans already have type 2 diabetes.
The finding does not prove cause and effect, Rubin said, but it does indicate an association between taking antidepressants and increasing the risk of getting diabetes among those already at high risk.
But, Rubin cautions, "this definitely does not mean that people should stop taking their antidepressant medication. If you think you are at high risk for developing diabetes, talk to your doctor. Be sure you monitor your blood glucose very carefully."
The study is interesting, but "more research is needed," said Cathy Nonas, a registered dietitian and director of the diabetes and obesity programs at North General Hospital in New York City.
For years, Nonas noted, the "chicken-or-the-egg" debate has continued, with researchers trying to analyze which came first -- depression leading to diabetes or vice versa. Like Rubin, she emphasized that depression is a condition that can't be ignored. "You have to treat the depression. If you don't, people can become nonfunctional," she said.
For example, Nonas added, if one of her patients is on an antidepressant, she always asks about weight gain. "If they have gained weight recently, I call their psychiatrist to see if the person can be switched [to another antidepressant that may not cause as much weight gain]."
The issue is far from resolved. In another study presented at the meeting, researchers reported that while diagnosed depression has been associated with developing diabetes, those in their study who had glucose intolerance did not have any more depressive symptoms than did others with more normal glucose levels. In yet another study, researchers reported that depression interfered with a person's ability to manage their diabetes.
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