Elevated blood glucose after fever is considered to be caused by stress factors.
Fever is one of the stress factors for high blood sugar. When the body is under stress, the hypothalamic-pituitary-adrenal axis is activated, and the activation of inflammatory factors can lead to an increase in the secretion of glucagon (e.g., adrenaline, glucocorticoid, growth hormone, etc.), which in turn leads to the elevation of blood sugar.
However, the elevation of blood glucose caused by stress factors is usually temporary, and the blood glucose can basically be recovered after the elimination of stress factors. However, if the blood glucose continues to be too high, it is necessary to consider the possibility of diabetes mellitus, and interventions are required under the guidance of specialists if necessary.
If you experience elevated blood glucose after a fever, you should go to the hospital for treatment under the supervision of a doctor.