Pathologies associated with chronic metabolic disturbances like obesity, diabetes and dyslipidemia, constitute major contributors to the worldwide burden of disease, death and disability, and are acquiring a higher relevance every day. Several of these problems are a direct or indirect consequence of an insufficient action of insulin, which gives rise to a cluster of risk factors that potentiate the onset of cardiovascular atherosclerotic disease in the long term. This review adresses in a concise way the mechanisms of insulin action at the molecular level, as well as the way they can be affected by factors different to the genetic constitution of each individual.