NBME Form 27 Practice Test

Thiazolidinediones (TZDs) are a class of oral antihyperglycemics that primarily target peroxisome proliferator-activated receptors (PPARs), specifically PPAR-gamma. These receptors are nuclear hormone receptors that regulate gene expression involved in glucose and lipid metabolism. When TZDs bind to PPAR-gamma, they modulate the transcription of genes that improve insulin sensitivity in muscle and adipose tissue, thus aiding in the regulation of blood glucose levels. This action enhances the body’s response to insulin, promotes fatty acid storage, and reduces insulin resistance, making TZDs effective in the management of type 2 diabetes.

In contrast, insulin receptors are directly activated by insulin, while glucagon receptors are involved in increasing blood glucose levels through gluconeogenesis and glycogenolysis. Glucose transporters play a role in the uptake of glucose into cells but are not directly targeted by TZDs. Instead, these transporters may be indirectly affected due to the improved insulin sensitivity that results from PPAR-gamma activation.