What kind of feedback loop is the glucose-insulin feedback loop?

• A. Positive feedback loop
• B. Negative feedback loop
• C. Feedforward loop
• D. Neutral feedback loop

Answer: (B)

Glucose regulation by insulin is a negative feedback system that keeps blood sugar within a narrow range. After eating, blood glucose rises and signals pancreatic beta cells to release insulin. Insulin helps tissues take up glucose and signals the liver to store or convert it, so blood glucose falls back toward normal. As glucose returns to baseline, the stimulus for insulin release diminishes, preventing overshoot. This self-correcting response defines negative feedback: the outcome counteracts the initial change and restores balance. A positive feedback loop would amplify changes instead of reversing them, which isn’t how glucose levels are stabilized. A feedforward loop would involve anticipating a change before it occurs, which isn’t how insulin release is triggered in this context. Neutral feedback isn’t a recognized mechanism for this process.