PANCE Endocrinology Practice Test

Thiazolidinediones act as PPAR-γ agonists that mainly enhance insulin action in adipose tissue, promoting fat storage there and reducing lipolysis, which lowers circulating free fatty acids. This adipose-tissue effect increases the adipokine milieu (notably adiponectin) and improves insulin signaling in skeletal muscle as well. Together, these changes make adipose tissue and skeletal muscle the primary sites of improved peripheral insulin sensitivity. The brain and bone marrow aren’t major targets, and any hepatic insulin-sensitivity improvement tends to be indirect rather than a primary peripheral effect.