This relatively new class of drug helps combat insulin resistance by making your body more sensitive to insulin. The first thiazolidinedione was approved for sale in the U.S. in 1997. It was sold under the brand name Rezulin (troglitazone), but was pulled from the market in March 2000 due to the risk for severe liver problems.
Avandia and Actos were approved by the U.S. Food and Drug Administration in 1999.
In 2007, a study suggested that Avandia was associated with an increased risk of heart attack and heart failure, a condition in which the heart becomes enlarged and pumps inefficiently. Shortly after, another study found that Actos also boosted the risk of heart failure, although it reduced the risk of heart attack, stroke and death overall. Both studies were widely covered in the news.
Why Avandia and Actos Carry New Safety Warnings
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"There's a concern about the link between heart disease and the use of thiazolidinediones," says Dace Trence, MD, an endocrinologist and director of the Diabetes Care Center at the University of Washington Medical Center in Seattle. "There's a concern that [the drugs] will cause heart failure and that's always been a known risk but it's a bit more surprising that there's a link to heart attacks. It's not clear how strong that linkage is."
How It Works
The action of these medicines in treating type 2 diabetes is not completely understood. They improve the way cells in the body respond to insulin by lowering insulin resistance. Unlike some other medicines used to treat diabetes, they do not cause the pancreas to produce more insulin.
Pioglitazone may help in the treatment of high cholesterol by reducing triglycerides and increasing high-density lipoproteins (HDL) in the blood. Rosiglitazone increases high-density lipoproteins (HDL) and slightly increases low-density lipoproteins (LDL). If you have high LDL, this may be a factor in selecting pioglitazone over rosiglitazone. The long-term effects of thiazolidinediones on cholesterol levels and the incidence of heart disease are not known.
Unlike pioglitazone, rosiglitazone does not interact with certain medicines, such as the antibiotic erythromycin and birth control pills.
Why It Is Used
These medicines are not recommended as the first choice to lower blood sugar levels. Thiazolidinediones should be used only when other medicines have failed to lower blood sugar levels into a safe range.
The U.S. Food and Drug Administration (FDA) recommends that rosiglitazone and pioglitazone be used alone or in combination with sulfonylurea medications, metformin, or insulin shots.
How Well It Works
Clinical studies have shown that these medicines can effectively lower blood sugar levels.
The action of these medicines in treating type 2 diabetes is not completely understood. They improve the way cells in the body respond to insulin by lowering insulin resistance. Unlike some other medicines used to treat diabetes, they do not cause the pancreas to produce more insulin.
Pioglitazone may help in the treatment of high cholesterol by reducing triglycerides and increasing high-density lipoproteins (HDL) in the blood. Rosiglitazone increases high-density lipoproteins (HDL) and slightly increases low-density lipoproteins (LDL). If you have high LDL, this may be a factor in selecting pioglitazone over rosiglitazone. The long-term effects of thiazolidinediones on cholesterol levels and the incidence of heart disease are not known.
Unlike pioglitazone, rosiglitazone does not interact with certain medicines, such as the antibiotic erythromycin and birth control pills.
Why It Is Used
These medicines are not recommended as the first choice to lower blood sugar levels. Thiazolidinediones should be used only when other medicines have failed to lower blood sugar levels into a safe range.
The U.S. Food and Drug Administration (FDA) recommends that rosiglitazone and pioglitazone be used alone or in combination with sulfonylurea medications, metformin, or insulin shots.
How Well It Works
Clinical studies have shown that these medicines can effectively lower blood sugar levels.
Last Updated: July 11, 2006 
