Definition of Thiazolidinedione

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Thiazolidinedione: (Pronounced THIGH-ah-ZO-li-deen-DYE-own.) A class of drugs for type 2 diabetes that lower the blood sugar by increasing the sensitivity of cells to insulin. Insulin can then move glucose from the blood into cells for energy. These drugs also increase the HDL ("good") cholesterol.

Rezulin (troglitazone) was the first drug in this class in the US but was taken off the market because of liver toxicity. Sister compounds now available with a better safety profile include Actos (pioglitazone) and Avandia (rosiglitazone). The main contraindications to the use of these medications include liver disease and heart failure. These drugs can cause a significant increase in fluid retention and thereby increase the risk of heart failure by about 70%.