Under normal conditions, blood sugar levels are controlled within a narrow range by negative feedback. two hormones are involved in maintaining blood sugar levels at the set point (about 90 mg of glucose/100 ml of blood). when blood sugar levels rise above the set point, the hormone insulin signals the liver to absorb the excess sugar. when blood sugar levels drop below the set point, the hormone glucagon signals the liver to release its stored glucose to the bloodstream. in juvenile onset diabetes, the body doesn't produce enough insulin and insulin supplements are required.
based on your understanding of homeostasis, for negative feedback control of blood glucose levels to function properly.

Sensors or sensory receptors must sense any change in blood glucose levels.

Explanation:

A feedback system includes a receptor, control center, and effector. The receptors serve to sense the deviation from homeostasis and send the nerve impulses or chemical signals to the respective control center. The control center receives input from receptors and sends nerve impulses or chemical signals to the effectors to bring about the desired change to restore homeostasis.

Negative feedback regulation of blood sugar includes sensing the rise or drop in blood sugar levels by sensory receptors. This sensory information is sent to the control center which in turn commands the effectors (pancreas) to secrete insulin or glucagon hormones to lower down or raise the blood glucose levels. Feedback regulation does not work in the absence of any of the components (sensory receptor, control center, and effector).