The American Heart Association (AHA) and American Diabetes Association (ADA) today issued recommendations to guide the use of glucose-lowering drugs known as thiazolidinediones (TZDs), such as Actos and Avandia.
"There is now widespread use of TZDs in a broad group of patients with type 2 diabetes. At the same time there have been reports of congestive heart failure associated with their use," says researcher Richard W. Nesto, MD, chair of the department of cardiovascular medicine at the Lahey Clinic in Burlington, Mass., in a news release.
Researchers say that in some people, Actos and Avandia may cause fluid retention, a condition known as edema, and swelling of the feet. Edema is also a classic symptom of congestive heart failure. The increase in fluid retention and therefore weight gain is usually seen in the first weeks after initiating therapy and then plateaus.
"It is sometimes difficult to know whether such swelling is a benign side effect of the drugs or a more ominous sign of heart failure," says Nesto. "It is this common association that concerns both cardiologists and diabetologists."
Diabetes Treatment and Congestive Heart Failure
Diabetes is a major risk factor for heart disease, and researchers stress that treatment with these diabetes drugs may actually lower risk of other heart disease risk factors such as high blood pressure, high cholesterol, and inflammation.
But because edema is a well-known side effect of these drugs, especially when combined with insulin therapy, researchers say that patients and health-care providers should be aware of the risk of congestive heart failure when using Actos and Avandia.
According to a consensus statement released by the AHA and ADA in the Dec. 9 issue of Circulation: Journal of the American Heart Association, people with moderate to severe congestive heart failure should not use these drugs.
People who do not have symptoms of congestive heart failure or have mild edema may still be prescribed TZDs, but researchers say doctors and their patients with type 2 diabetes should watch for signs of fluid retention especially to some degree when these drugs are prescribed with insulin.
The guidelines call for a "start low, go slow" approach when considering the use of these drugs in people who do not have congestive heart failure but do have one or more of the following risk factors for congestive heart failure:
- Heart attack
- History of heart failure
- High blood pressure
- Enlargement of the left ventricle
- Heart valve disease
- Age older than 70
- Long-standing diabetes
- Chronic renal failure
- History of edema
Researchers say clinical trials are currently underway to better understand the link between these diabetes drugs and congestive heart failure.
"But at this point we don't know the real risk because we don't know either the actual number of patients with diabetes who are taking a TZD and develop congestive heart failure, compared to the total number of patients who are taking a TZD," says Nesto. "This risk is probably quite low, but without solid data that's just guesswork."