Beta-cell behavior during the prediabetic stage. Part I. Beta-cell pathophysiology.

beta-Cell function in non-insulin dependent diabetes mellitus (NIDDM) or type II diabetes, in particular during the prediabetic stage, has been more extensively investigated than in insulin-dependent diabetes mellitus (IDDM) or type I diabetes. Recently, however, the existence of a beta-cell dysfunction, early during the prediabetic stage of IDDM, and its possible contribution to the amplification of the autoimmune reaction have been underlined. Here, in a first of two parts, an attempt is made to review the various ways normal beta cells cope with increased demands on their resources in different models of hyperglycaemia in order to better delineate and compare the mechanisms implicating beta cells in the pathogenesis of both types of diabetes.