Taking drugs for depression linked to better diabetes control

People who have both diabetes and depression may have an easier time keeping their blood sugar levels under control if they also take medication to address their mental health symptoms, a U.S. study suggests.

Diabetics can be more prone to depression and stress than other individuals, and these mental health problems are linked to increased risks of dangerously high blood sugar levels and other serious complications, previous research has found.

When diabetics do get depressed, however, taking antidepressants is linked to 95 percent higher odds that their blood sugar will be well controlled, the current study found.

“We don’t know the mechanism by which the use of antidepressants is associated with better blood sugars in those patients with both conditions,” said lead study author Dr. Jay Brieler of Saint Louis University School of Medicine.

It’s possible that when depression improves, people may be more likely to follow a healthy diet, exercise, check their blood sugars and keep up with medications for diabetes, Brieler said by email.

Scientists are also exploring whether there’s a physiologic connection between the two diseases, which might mean shifts in stress hormones tied to antidepressant use might also affect blood sugars.

“Regardless of the mechanism, I think that our study adds to the evidence that it is important to properly diagnose and treat depression in diabetics,” Brieler added.

Brieler and colleagues reviewed electronic medical records for about 1,400 diabetics, including lab tests for blood sugar and prescription data on antidepressant use, from 2008 to 2013.

On average, patients were around 62 years old. Most were obese. All of them had type 2, or adult-onset, diabetes, which happens when the body can't properly use or make enough of the hormone insulin to convert blood sugar into energy.

Many had other health problems, too, such as high blood pressure or cholesterol. Most – 1,134 of them – didn’t suffer from depression, but the study included 225 people being treated for depression and 40 individuals who were diagnosed with depression but were not taking medication for it.

Researchers estimated average blood sugar levels over the course of several months by measuring the percentage of hemoglobin – the protein in red blood cells that carries oxygen – that is coated with sugar.

This sugar-coated form of hemoglobin is known as hemoglobin A1c, or HbA1c. With diabetes, keeping HbA1c test results below 7 percent is generally considered to be good blood sugar control.

Overall, only 44 percent of diabetics in the study had their blood sugar under control, or below 7 percent, and average HbA1c levels were 7.7 percent.

About 51 percent of people with treated depression had their blood sugar under control, compared to only 35 percent of those with untreated depression.

One limitation of the study is that researchers couldn’t determine whether treating depression led to better blood sugar control or whether lowering blood sugar eases depression symptoms, the authors acknowledge in Family Practice. Both scenarios are possible.

It’s also important for patients to know that certain antidepressants and antipsychotics can be associated with weight gain and poor blood sugar control, noted Dr. Robert Cohen, a researcher at the University of Cincinnati College of Medicine and the Cincinnati VA Medical Center who wasn’t involved in the study.

“That’s why it is important to have those medications prescribed by a health care provider who will be following along closely enough to detect that and determine when changes are needed,” Cohen said by email.

These risks shouldn’t deter diabetics from seeking depression treatment, however. “From my experience, getting depression under control by whatever means can help people overcome their inertia that prevents them from making their best efforts to deal with their diabetes,” Cohen added.