Two drugs frequently prescribed to diabetics to aggressively lower blood sugar - pioglitazone and rosiglitazone - have been found to increase significantly the risk of developing heart failure. The two medications, which belong to a group of drugs known as thiazolidinediones, have been found to actually double the risk of developing congestive heart failure (CHF). The increased risk is so significant, in fact, that the research team publicly questions the validity of prescribing thiazolidinediones at all.

Diabetes is strongly associated with heart disease, with approximately 22% of all people diagnosed with type 2 diabetes also diagnosed with heart disease. Elderly diabetic patients run a 50-50 risk of developing congestive heart failure within ten years.

Diabetes elevates blood pressure rates and levels of cholesterol and triglycerides, three elements that can lead to the development of ischemic heart disease. Two of the most-telling predictors of heart failure are heart disease and hypertension, or high blood pressure.

Thiazolidinediones meet federal approval standards for lowering blood sugar levels but a review of several major studies involving the cardiovascular effects of these drugs leaves the research team from Wake Forest University School of Medicine saying justification for their use is “very weak to non-existent” at this time and may actually make congestive heart failure worse.

Reporting that thiazolidinediones double a type 2 diabetic’s risk of developing CHF across the full spectrum of drugs in their class, the research team points to three large and randomized clinical trials whose results were published in June 2008. In each of the trials, scientific study produced no evidence that controlling blood sugar reduces the number of deaths or other cardiovascular events in people suffering from both type 2 diabetes and cardiovascular disease.

One study, known as ACCORD, revealed a doubled risk of death from cardiovascular disease when type 2 diabetics took thiazolidinediones to treat elevated blood sugar than when another, more conventional, oral agent was prescribed.

The ADVANCE study revealed no benefit to taking thiazolidinediones to lower blood sugar levels. The same study reported no increased risk of cardiovascular event or death between patients taking thiazolidinediones and those taking standard oral medications for diabetes treatment.

The third study, the Veterans Affairs (VA) Diabetes study found that aggressively treating elevated sugar levels with thiazolidinediones can cause sugar levels to drop dangerously low, low enough in some cases to induce unconsciousness. Loss of consciousness due to low blood sugar levels is a very strong indicator that heart disease is in the future.

Sonal Singh, MD, MPH, and Curt D. Furberg, MD, PhD, are concerned that the medical community has not fully realized the potential risks associated with using thiazolidinediones as a means of intensive therapy to reduce blood sugar levels. The researchers, a Wake Forest assistant professor of internal medicine and professor of public health sciences, respectively, suggest using safer, cheaper drugs that have been proven to be more effective. The drugs the research team prefers do not carry increased cardiovascular risk as the thiazolidinediones do.

The online issue of Heart carries an editorial published by the researchers that describes their study and its conclusions.

Source: Wake Forest University Baptist Medical Center