Why does decreased muscle mass (sarcopenia) during aging exacerbate insulin resistance in skeletal muscle?

💡 Explanation

Skeletal muscle expresses GLUT4 to uptake glucose in response to insulin. Sarcopenia diminishes the muscle's capacity, reducing GLUT4 translocation and thus glucose uptake; because less glucose is removed from the blood, insulin resistance is worsened. Therefore, reduced GLUT4 translocation is the answer, rather than myokine release or mTOR signaling, which would improve glucose metabolism.

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