β-Hydroxypyruvate: a new diabetogenic factor?

Abstract

The incidence of type 2 diabetes mellitus (T2DM) is increasing at an alarming rate. Insulin secretory dysfunction and insulin resistance are characteristic features of T2DM. However, their relative contributions to the progression from normal glucose tolerance to impaired glucose tolerance (IGT) to T2DM remain unknown. This limits the capacity of researchers to establish therapeutic interventions for T2DM. Glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 are the two primary incretin hormones secreted by intestinal K and L cells, respectively. Secretion of these incretins increases postprandially and they potentiate glucose-stimulated insulin secretion (GSIS). Despite blunted incretin responses in patients with T2DM, insulinotropic responses to exogenously administered GLP-1 remain active in these patients (1). Although controversy exists, a recent study demonstrated that insulin secretory responses to GIP were retained in patients with T2DM (1,2). Additionally, incretin response to GIP is improved by reducing blood glucose levels in patients with T2DM (3). These findings support the rationale for use of incretin-based pharmacotherapies in the treatment and management of T2DM. However, identification of the mechanism by which the function of K cells contributes to the development of T2DM is still elusive and requires a good model of study. To determine the role of K cells in the regulation of metabolism, K cells were eliminated from mice by expressing the diphtheria toxin A-chain gene in GIP-producing cells (DT mice). Despite a severely impaired …