Insulin resistance (IR) describes impaired hormone signaling that triggers compensatory homeostatic responses resulting in hyperinsulinemia, increased accumulation of fatty substrates, lipotoxicity, oxidative stress, inflammation, cell death and fibrosis in target tissues. These processes ultimately lead to organ dysfunction and predispose certain individuals to various types of cancer. In this context, we will review the molecular pathogenesis and clinical significance of IR, its role in ‘metaflammation’, and the damage caused by IR in the pancreas, cardiovascular system, liver, and kidneys. Additionally, we will discuss principles of drug treatment for IR and outline a research agenda in this field.