Thiazolidinediones for type 2 diabetes

Insulin resistance, or more appropriately the reduced action of insulin, is a prominent defect in type 2 diabetes.1 It is commonly present in people before diabetes has developed and has even been observed in euglycaemic relatives of patients with type 2 diabetes.2 It has been proposed that the reduced action of insulin is fundamental to the cardiovascular risk factors that are part of the syndrome of insulin resistance.3 Avoidance of obesity and adequate levels of physical activity are non-pharmacological cornerstones of the fight against insulin resistance. Before the introduction of troglitazone in 1997 metformin was the only drug able to sensitise target tissues (skeletal muscle, adipose tissue, and the liver) to insulin. Troglitazone was the first of a new class of drugs with direct insulin sensitising actions—the thiazolidinediones (also known as glitazones).4 Troglitazone has now been superseded by more potent agents, rosiglitazone and pioglitazone. Thiazolidinediones activate nuclear peroxisome proliferator activated receptor γ (PPAR-γ), which is expressed predominantly in adipose tissue. 4 5 Insulin action is improved through the increased transcription of …