Final answer:
Eating watermelon and white rice leads to an increase in blood glucose levels due to their high glycemic index. Insulin is then released to lower these high blood sugar levels, but in diabetes, the glucose levels may remain elevated. Finally, glucagon is released when blood sugar levels fall too low, to increase them back to normal.
Step-by-step explanation:
Watermelon and white rice cause blood glucose to increase rapidly. Following this, blood glucose levels decrease as the body responds to manage the heightened sugar levels.
After consuming foods with a high glycemic index, such as watermelon and white rice, there is a rapid absorption of sugars into the bloodstream, leading to a spike in blood glucose levels. This is a condition known as hyperglycemia, where blood glucose levels can rise above 180-360 mg/100 ml. In response, the beta cells of the pancreas release insulin which facilitates the conversion of the excess glucose into glycogen in the liver. As a result, the elevated blood glucose levels then decrease to more normal ranges.
However, in conditions like diabetes mellitus, there can be a lack of proper response to insulin, resulting in a continuous high blood sugar level even several hours after eating. On the other hand, when blood sugar concentrations drop too low, the pancreas releases glucagon instead of insulin, stimulating the liver to release glucose and thereby increase blood sugar levels.