Type 2 diabetes-a matter of beta-cell life and death?

In type 2 diabetes, the beta cells of the pancreas fail to produce enough insulin to meet the body's demand, in part because of an acquired decrease in beta-cell mass. In adults, pancreatic beta-cell mass is controlled by several mechanisms, including beta-cell replication, neogenesis, hypertrophy, and survival. Here, I discuss evidence supporting the notion that increased beta-cell apoptosis is an important factor contributing to beta-cell loss and the onset of type 2 diabetes. Interestingly, a key signaling molecule that promotes beta-cell growth and survival, insulin receptor substrate 2 (IRS-2), is a member of a family of proteins whose inhibition contributes to the development of insulin resistance in the liver and other insulin-responsive tissues. Thus, the IRS-2 pathway appears to be a crucial participant in the tenuous balance between effective pancreatic beta-cell mass and insulin resistance.