Insulin resistance (IR) plays not only a dominant role in the pathogenesis of diabetes mellitus and its complications, but it is the most important factor for the development of age-related pathology responsible for the body's accelerated aging. There is no consensus on the underlying cause of IR to this day. There are several known theories, each of which describes individual components of the process and only together they represent a more or less coherent picture. IR is known to join complex bilateral relations with cell aging processes, being their portrayal, on the one hand, and an influencing factor, on the other. The case in point is first the relationship of IR to ones of the most important markers of biological aging and to the cardiovascular risk - telomere length and telomerase activity. IR is of great importance for the development of poor aging phenotypes and age-related diseases. Its negative impact on life span is not so clear. On the one hand, IR favors the development of metabolic disturbances and related diseases (atherosclerosis, diabetes mellitus) and, on the other hand, ensures some protective mechanisms contributing to longevity. Further investigations of the pathogenesis of IR and the mechanisms responsible for its association with obesity and inflammation will aid in opening new vistas for preventing and treating metabolic, age-related, and cardiovascular diseases. This review discusses the mechanisms of IR, its role in the development of main age-related vascular changes and in the transformation of vascular aging processes to disease, and the contribution of IR to lifetime.