Antidepressants linked to increased risk of diabetes in high-risk patients

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Study findings show a link between antidepressant use and diabetes, investigators here at the 66th Scientific Sessions of the American Diabetes Association announced. This is the first report of such an association, they say.

Depression is two to three times higher in diabetics than in the general population. In addition, 10%-15% of the US population takes antidepressants, "and the numbers are increasing," Dr. Richard R. Rubin of The Johns Hopkins University School of Medicine in Baltimore, Maryland, told meeting attendees Saturday.

Dr. Rubin is a co-investigator with the Diabetes Prevention Program Research Group. He presented findings from the 3187 participants in the trial with elevated blood glucose values showing that they were pre-diabetic. Of these, 5.7% reported regular use of antidepressants at baseline. Elevated scores on the Beck Depression Inventory were found in 10.3%.

Patients were randomized into three study arms: metformin therapy, intended to prevent the onset of diabetes; intensive lifestyle modification; or placebo. Mean length of follow-up was 3.2 years.

High scores on the Beck Depression Inventory by themselves did not predict the development of diabetes. However, after controlling for weight and baseline metabolic and demographic factors, the investigators found that antidepressant use did, with a hazard ratio of 1.9 in the placebo group and 2.8 in those in the intensive lifestyle modification arm. There was no increased risk of diabetes associated with depression in the metformin arm.

"We don't have a clue" as to why the association exists, Dr. Rubin told Reuters Health. In their abstract the investigators say the mechanism "does not appear to be increased weight or fasting plasma glucose or insulin levels."

Metformin acts primarily in the liver, and may change the body's response to antidepressants. "Or, the drug could be a marker for something else," Dr. Rubin suggested.

If the findings are confirmed in further studies, "it would have enormous public health implications," he commented. "In the meantime, patients should not stop taking their antidepressants. They have been proven to have tremendous relief, but those at risk of diabetes should have their blood sugar monitored frequently and perhaps - perhaps - begin oral anti-diabetic treatment early."

Dr. Rubin emphasized that patients in this study were all at very high-risk for developing diabetes.