Inadequate blood supply can cause dizziness, mostly in patients with inadequate blood supply to the cerebellum and brainstem. Patients with inadequate cerebellar blood supply may experience dizziness, nausea, and vomiting, while patients may develop nystagmus, ataxia on the side of the lesion, unsteadiness in standing and gait, hypotonia, dysarthria, chanting-like speech, and patients generally do not have signs of hemiparesis. Patients with inadequate blood supply to the brainstem may present with dizziness, headache, nausea, vomiting, diplopia, disparate axes of the eyes, lateral visual palsy, crossed paralysis or hemiparesis, quadriplegia, etc. Inadequate blood supply is the main manifestation of cerebral atherosclerosis. The main risk factors of cerebral atherosclerosis include high blood lipids, high blood pressure and high blood sugar. Patients with inadequate blood supply should be monitored for blood sugar, blood lipids and blood pressure in a timely manner.