Restoring a functional β-cell mass in diabetes

Abstract

Type 1 and type 2 diabetes have often been presented as disease forms that profoundly differ in the presence and pathogenic significance of a reduced β-cell mass. We review evidence indicating that the β-cell mass in type 1 diabetes is usually not decreased by at least 90% at clinical onset, and remains often detectable for years after diagnosis at age above 15 years. Clinical and experimental evidence also exists for a reduced β-cell mass in type 2 diabetes where it can be the cause for and/or the consequence of dysregulated β-cell functions. With β-cell mass defined as number of β-cells, these views face the limitation of insufficient data and methods for human organs. Because β-cells can occur under different phenotypes that vary with age and with environmental conditions, we propose to use the term functional β-cell mass as an assessment of a β-cell population by the number of β-cells and their phenotype or functional state. Assays exist to measure functional β-cell mass in isolated preparations. We selected a glucose-clamp test to evaluate functional β-cell mass in type 1 patients at clinical onset and in type 1 recipients following intraportal islet cell transplantation. Comparison of the data with those in non-diabetic controls helps targeting and monitoring of therapeutic interventions. © 2008 The Authors Journal Compilation © 2008 Blackwell Publishing Ltd.