What happens when cells are exposed to too much insulin, according to the described mechanism of Type 2 diabetes?

• A. Insulin becomes more effective.
• B. Cells start producing more insulin.
• C. The receptor sites increase in number.
• D. Receptors become 'blind' or burn out.

Answer: (D)

When cells are exposed to too much insulin, their signaling machinery downregulates to protect against overstimulation. This desensitization means the insulin receptors become less responsive or fewer in number on the cell surface, so the insulin signal is weaker and glucose uptake is reduced. This is the hallmark of insulin resistance seen in Type 2 diabetes: despite high insulin levels, cells don’t respond as well, leading to higher blood glucose.

This is why the idea of receptors becoming “blind” or burn out fits best. It reflects the reduced receptor effectiveness after chronic exposure. The other ideas don’t match the observed mechanism: insulin does not become more effective with chronic exposure; the body isn’t typically increasing receptor numbers under this circumstance; and while the pancreas may compensate by making more insulin, that’s a separate response and not the direct effect of too much insulin on target cells.