High blood glucose after exercise may be caused by elevated glucose levels and increased sympathetic excitability. 1. Exercise consumes glucose, and low glucose stimulates the breakdown of hepatic glycogen into glucose, which leads to elevated blood glucose when the glucose level in the body is too high. 2. When the body exercises, the sympathetic nerve excitability increases, leading to an increase in the secretion of catecholamines, epinephrine and norepinephrine by the adrenal medulla, which can lead to the decomposition of hepatic glycogen and increase blood glucose concentration. Moderate exercise can help control blood glucose levels. If abnormal blood glucose levels are found after exercise, prompt medical attention is recommended.