Diabetics who use oral drugs to control their disease face a 50 percent increase in the risk for heart failure compared to those who do not take use the drugs, researchers said Tuesday at a American College of Cardiology conference.
The drugs belong to a class of drugs called glitazones and are sold under brand names Avandia and Actos. These drugs are used to treat type 2 or adult onset diabetes, which is the most rapidly increasing type of diabetes. A third glitazone, Rezulin, was withdrawn from the market two years ago because of severe liver toxicity side effects.
Thomas Delea, a researcher with Policy Analysis Inc. in Brookline, Mass., analyzed records of claims from 35 health insurers covering 1.7 million Americans. He identified 8,288 diabetics taking glitazones and 41,440 who did not take the drugs and then compared claims over a 36-month period from the time of the first prescription for a glitazone.
Diabetes itself is a risk factor for heart disease, including heart failure, which causes fluid retention and extreme breathlessness as the heart struggles to pump blood to vital organs.
After 36 months, patients taking glitazones faced a “4.5 percent risk of developing heart failure,” said Delea. “Diabetics who didn’t take glitazones had 2.6 percent risk.”
After he controlled for other risk factors, such as obesity, high blood pressure and smoking, glitazone remained an independent predictor for heart failure and compared to non-users “there was still a 50 percent increase in risk for heart failure,” he said.
Delea did caution the findings are based on “observational data and need to be confirmed in a clinical trial.”
Dr. John Buse, who heads a special committee on heart disease at the American Diabetes Association, said the oral drugs, used to control sugar levels in the blood, are useful medications but need to be carefully monitored.
He said package inserts included with the drugs warn they can cause fluid retention as well as plasma volume expansion, both factors associated with heart failure.
“The problem is that the people who need these drugs are the people who are already at the highest risk for heart failure,” Buse said.
Adult onset diabetes can be controlled by diet, exercise and strict blood pressure control. But in some patients, these lifestyle changes do not reduce blood sugar to normal levels and medications are needed.
Delea agreed with this assessment, noting glitazone users in his study were “older and were more likely have other risk factors for heart failure.”
He added these patients also were likely to have a history of higher health costs, suggesting they were generally sicker than diabetics who did not use glitazone.