ABSTRACT Sulfonylureas, commonly used to treat type 2 diabetes (T2D), often lose effectiveness over time when used as monotherapy; however, the underlying mechanisms remain unclear. To investigate the mechanisms of sulfonylurea failure, glibenclamide‐releasing pellets were implanted in KK mice, a polygenic model that spontaneously develops T2D. KK mice receiving placebo pellets (KK‐Placebo) developed hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Notably, KK mice implanted with glibenclamide (KK‐Glib) showed improved blood glucose levels during the first 7 days, returning to KK‐Placebo levels thereafter. KK‐Glib mice exhibited reduced plasma insulin levels and insulin secretion in response to a glucose challenge compared with the markedly elevated levels in KK‐Placebo mice. KK‐Glib mice showed islet hypertrophy, reduced β‐cell mass and number, and increased α‐cell number, resulting in elevated α:β cell ratio compared with KK‐Placebo. Although mRNA expression of β‐cell identity markers remained unchanged, their protein levels were reduced in KK‐Glib, suggesting β‐cell identity loss, which may underlie the observed impaired insulin secretion. Remarkably, KK‐Glib mice showed elevated mRNA levels of Ngn3 (dedifferentiation) and α‐cell identity markers along with glucagon content, suggesting α‐cell neogenesis. These findings suggest that secondary failure of sulfonylurea therapy may, in part, result from loss of β‐cell identity‐function and increased α‐cell number‐identity.
Patel et al. (Sun,) studied this question.