Glucolipotoxicity in Pancreatic beta-Cells

ABSTRACT

The recent epidemic of type 2 diabetes in Asia differs from that reported in other regions of the world in several key areas: it has evolved over a much shorter time, in an earlier stage of life, and in people with lower body mass indices. These phenotypic characteristics of patients strongly suggest that insulin secretory defects may perform a more important function in the development and progression of diabetes. A genetic element clearly underlies beta-cell dysfunction and insufficient beta-cell mass; however, a number of modifiable factors are also linked to beta-cell deterioration, most notably chronic hyperglycemia and elevated free fatty acid (FFA) levels. Neither glucose nor FFAs alone cause clinically meaningful beta-cell toxicity, especially in patients with normal or impaired glucose tolerance. Thus the term "glucolipotoxicity" is perhaps more appropriate in describing the phenomenon. Several mechanisms have been proposed to explain glucolipotoxicity-induced beta-cell dysfunction and death, but its major factors appear to be depression of key transcription factor gene expression by altered intracellular energy metabolism and oxidative stress. Therefore, stabilization of metabolic changes induced by glucolipotoxicity in beta-cells represents a new avenue for the treatment of type 2 diabetes mellitus.