Dizziness, blurred vision and sweating may be due to insufficient blood supply to the brain. Insufficient blood supply to the brain includes insufficient blood supply to the internal carotid artery system and insufficient blood supply to the vertebral basilar artery system. When the blood supply to the vertebral basilar artery system is insufficient, patients generally show signs and symptoms of ischemia and hypoxia in the cerebellum and brainstem, and may experience dizziness, nausea, vomiting, impaired balance, and ataxia. When the blood supply to the internal carotid artery system is inadequate, patients generally present with blackness in front of the eyes and may also present with weakness of the extremities. Some patients may present with signs and symptoms of vegetative nerve function. Patients mainly present with palpitations, chest tightness, sweating, and some patients may also present with urinary and bowel disorders. It may also be caused by hypoglycemia, which can easily cause cerebral hypoxia. If the patient suffers from cerebellar and brainstem hypoxia, dizziness may occur, and when the brain is hypoxic, the patient can generally have blackness in front of the eyes, and can also have blurred vision. Patients may also suffer from memory loss and inattention, etc.