What causes hyperglycemia during exercise according to the text?

Hyperglycemia during exercise is primarily caused by the release of glucagon, which is a hormone that plays a crucial role in regulating glucose levels in the blood. During exercise, the body experiences increased energy demands, prompting the release of glucagon from the alpha cells of the pancreas. This process stimulates the liver to convert glycogen stores into glucose, which is released into the bloodstream to provide the necessary energy for physical activity.

While insulin overdose, inadequate glucose intake, and reduced physical activity can affect blood glucose levels, they are not the primary contributors to hyperglycemia during exercise. Insulin typically lowers blood glucose levels; an overdose would usually lead to hypoglycemia rather than hyperglycemia. Inadequate glucose intake before exercise might lead to low blood sugar levels instead of high. Likewise, reduced physical activity does not correlate with the hyperglycemic response seen during active exercise since exercise typically enhances glucose uptake by muscles when insulin is functional. Thus, the role of glucagon is essential in facilitating the needed release of glucose to meet the elevated energy demands during exercise, leading to hyperglycemia.