High luminal concentrations of glucose in vivo cause the activation and insertion of GLUT2 into the apical membrane of rat jejunum. Activation and insertion are dependent in part on transport of glucose through SGLT1, which both activates the Ca⁺⁺-requiring enzyme PKC βII and causes cytoskeletal rearrangement through Ca⁺⁺-dependent contraction of the perijunctional actomyosin ring. Recent experiments reveal that luminal Ca⁺⁺ is essential for GLUT2 insertion and enters the enterocyte by an L-type channel, most likely Ca_v1.3; both apical GLUT2 insertion and Ca⁺⁺ absorption are regulated by L-type effectors. Contraction of the perijunctional actomyosin ring is also essential for apical GLUT2 insertion; inhibition of myosin II phosphorylation with the myosin light chain kinase inhibitor, ML7, inhibits insertion and GLUT2-mediated absorption, but has no effect on Ca⁺⁺ absorption. Paracellular flow of glucose is negligible when assessed using ^14C-mannitol as a tracer. Glucose and other sugars cause the rapid turnover and degradation of PKC βII by a pathway involving cleavage, dephosphorylation and ubiquitylation. The data are consistent with the view that SGLT1, PKC βII and Ca⁺⁺ are among key elements in an intestinal sugar sensing system, which targets the rapid upregulation of glucose absorption through apical GLUT2 to match dietary intake.