Birth of a Microdomain: Can Glucose Act as a Metabolic Switch?

Glucose homeostasis is an essential physiological process to ensure a stable energy supply to all tissues while preventing the harmful consequences of hypo- or hyperglycemia. The endocrine pancreas plays a central role in maintaining this process, where β-cells and α-cells secrete insulin and glucagon to coordinate systemic glucose metabolism, storage, and production. In this context, β-cells act as the main glucose sensors, closely linking extracellular glucose fluctuations to insulin release. This sensing is dependent on glucose transporters (GLUTs), which regulate cellular glucose uptake through their dynamic trafficking to the plasma membrane. The resultant increase in ATP links metabolism to electrical activity and exocytosis of insulin granules. β-cells maintain plasma glucose within the physiological range of 4-5.5 mM by integrating glucose uptake with metabolic signaling, thereby lowering elevated postprandial concentrations to ∼7.8 mM. In type 2 diabetes, defects in GLUT regulation reduce β-cell responsiveness, impair insulin secretion, and destabilize glucose homeostasis, highlighting GLUT dynamics as a target to maintain normoglycemia.