TZDs, which are pure PPARγ full agonists, have been widely used to treat T2DM for nearly 20 years and are referred to as the classical “insulin sensitizers,” as they act to restore blood glucose to normal levels by increasing the insulin sensitivity of target tissues without the risk of causing hypoglycemia, unlike agents such as secretagogues. The gene discussed is PPARG; the disease is type 2 diabetes mellitus.