Question
Which of the following tissues will not be able to take up glucose in insulin resistance/insulin absence/diabetes mellitus?
| A. |
Skeletal muscle
|
| B. |
Red blood cells
|
| C. |
Brain
|
| D. |
Kidney
|
Show Answer
|
Correct Answer � A
Explanation
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|
Glucose uptake in skeletal muscle is primarily mediated by the GLUT-4 transporter, which is insulin-dependent. In conditions of insulin resistance or absence (as in diabetes mellitus), insulin signaling is impaired, and GLUT-4 transporters are not effectively translocated to the cell membrane. As a result, glucose uptake by skeletal muscle is significantly reduced. This leads to hyperglycemia and decreased glucose utilization in peripheral tissues like skeletal muscle, adipose tissue, and heart, all of which depend on GLUT-4.
Reason to rule out other options:
B. Red blood cells:
• Red blood cells use GLUT-1 transporters for glucose uptake, which are insulin-independent.
• They can continue to take up glucose even in the absence of insulin.
C. Brain:
• The brain primarily utilizes GLUT-1 (at the blood-brain barrier) and GLUT-3 (in neurons), both of which are insulin-independent.
• Glucose uptake remains largely unaffected by insulin deficiency.
D. Kidney:
• Renal tubular cells use GLUT-2 transporters for glucose reabsorption, which are insulin-independent.
• The kidneys continue to take up and reabsorb glucose even in insulin-resistant states.
