Final answer:
In individuals with type I diabetes, aerobic exercise without sufficient insulin can lead to increased blood glucose levels because the body's normal response to regulating blood sugar by insulin is impaired, leading to a continued release of glucose from the liver.
Step-by-step explanation:
If insulin levels are markedly decreased when a type I diabetic begins exercise, continuous aerobic exercise would result in an increase in blood glucose concentration.
This is because insulin normally helps to sequester glucose from the blood into cells. In individuals with type I diabetes, their pancreas fails to produce adequate insulin, leading to a poor regulation of blood glucose levels.
During exercise, the body needs more glucose for energy, and with the lack of insulin's regulatory effect, the liver continues to release glucose into the bloodstream through processes like glycogenolysis and gluconeogenesis. Consequently, without sufficient insulin to facilitate glucose uptake into cells, blood glucose levels can rise.