The glucose sink concept refers to skeletal muscle's massive capacity to take up and dispose of blood glucose, independent of insulin in some contexts.
Mechanism: Muscle contraction triggers GLUT4 translocation to the cell membrane, pulling glucose in without requiring insulin signaling. A single hard training session improves glucose disposal for 24-48 hours afterward.
Use case: Resistance training, walking after meals, high-intensity intervals. Building muscle increases the size of the sink.
Caveats: A small, sedentary person has a small sink. Glucose tolerance closely tracks lean muscle mass.