High estradiol in a 5-year-old girl does not usually cause hyperglycemia, and elevated blood glucose is usually caused by insulin secretion disorders or impaired pancreatic islet function. Estradiol is a kind of estrogen, which is mainly used for the development and maintenance of female secondary sex characteristics and regulation of menstrual cycle, etc. It is generally not related to glucose metabolism. Pancreatic islets are organs that secrete insulin, which has the effect of lowering blood sugar. If the function of the pancreatic islets in the body is impaired, it may lead to insufficient secretion of insulin, which may lead to elevated blood sugar in the body; or there may be insulin resistance, which may lead to the inability of insulin to play its role properly, thus leading to elevated blood sugar. If a 5-year-old girl has elevated blood glucose, she should consult a doctor in time to check whether there is any abnormality in the function of pancreatic islets and insulin secretion, and she should pay attention to a reasonable diet and exercise in her daily life.