High and low blood glucose in the elderly is dangerous and may cause hypoglycemic coma or ketoacidosis, and may also cause cardiovascular events such as stroke and myocardial infarction, which need to be taken seriously. If there is no history of diabetes and blood glucose is high or low, the possibility of diabetes cannot be ruled out. It is recommended to consult an endocrinologist to improve the glucose tolerance test and glycated hemoglobin and other tests to clarify the diagnosis. If there is a history of diabetes mellitus, blood glucose is high and low, indicating that blood glucose fluctuation, poor blood glucose control, hypoglycemia may occur coma, impaired consciousness, high blood glucose may occur ketoacidosis, lactic acidosis and other emergencies. It may also induce acute adverse cardiovascular events such as stroke and myocardial infarction. Long-term blood glucose fluctuations may lead to the premature emergence of chronic complications of diabetes, such as diabetic nephropathy, diabetic peripheral neuropathy, diabetic retinopathy and so on. Elderly people with fluctuating high and low blood glucose need prompt medical attention.