From ScienceDaily, research that provides an interesting view of the insulin signaling mechanism, metabolism and its impact on life span: "The traditional prescriptions for a healthy life - sensible diet, exercise and weight control - extend life by reducing signaling through a specific pathway in the brain [activated] when insulin and insulin-like growth factor-1 switch on proteins inside the cell called insulin receptor substrates ... Diet, exercise and lower weight keep your peripheral tissues sensitive to insulin. That reduces the amount and duration of insulin secretion needed to keep your glucose under control when you eat. Therefore, the brain is exposed to less insulin. Since insulin turns on [an insulin receptor substrate] in the brain, that means lower [insulin receptor substrate] activity, which we've linked to longer lifespan in the mouse ... We are beginning to appreciate that obesity, insulin resistance, and high blood insulin levels are connected to Alzheimer's disease, Huntington's disease, and dementias in general. It might be that, in people who are genetically predisposed to these diseases, too much insulin overactivates [insulin receptor substrates] in the brain and accelerates disease progression. Thus, insulin resistance and higher insulin levels might be the environmental influences that promote these diseases."