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Insulin GLUT4 Mechanism — FRCA Primary MCQ

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HardPhysiology - Endocrine & MetabolicInsulin GLUT4 MechanismFRCA Primary

After insulin administration, skeletal-muscle glucose uptake rises. Which transport event is responsible for the rapid component of this response?

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Correct answer: B — Translocation of preformed GLUT4-containing vesicles to the plasma membrane

The best answer is “Translocation of preformed GLUT4-containing vesicles to the plasma membrane”. Insulin rapidly recruits intracellular GLUT4 vesicles to the plasma membrane of skeletal muscle and adipose tissue, increasing facilitated glucose uptake. SGLT2 is a renal proximal-tubule transporter and GLUT2 is important in liver, beta cells and renal basolateral membranes. Hepatic glycogenolysis raises, rather than lowers, circulating glucose.

Reference: RCoA, Primary FRCA syllabus: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf; Canonical and alternative pathways of GLUT4 recruitment: https://pmc.ncbi.nlm.nih.gov/articles/PMC13116035/