Insulin resistance is a pathological condition in which the body's cells—primarily in muscle, adipose tissue, and liver—exhibit a diminished response to insulin. As a compensatory mechanism, pancreatic beta cells increase insulin secretion to maintain euglycemia, but this compensation may eventually fail, leading to hyperglycemia and Type 2 diabetes. Insulin resistance plays a central role in the pathogenesis of several metabolic disorders, including obesity, prediabetes, metabolic syndrome, and cardiovascular disease. Mechanistically, it involves defects in insulin receptor signaling pathways, often exacerbated by inflammatory cytokines, ectopic fat deposition, mitochondrial dysfunction, and oxidative stress. Clinically, insulin resistance is often inferred from surrogate markers such as elevated fasting insulin, HOMA-IR, or triglyceride-glucose index. Lifestyle interventions—such as weight loss, physical activity, and dietary modifications—are the most effective means of improving insulin sensitivity. Pharmacologic agents like metformin and thiazolidinediones can also enhance insulin action. Given its pivotal role in metabolic health, early detection and intervention targeting insulin resistance can significantly reduce the risk of progression to Type 2 diabetes and associated complications.