Diabetic high blood sugar can be asymptomatic, or there can be three more and one less (more drinking, more eating, more urination, and weight loss), dizziness, fatigue and so on. 1. Three more and one less: three more and one less refers to drinking more, eating more, urinating more and losing weight, which is a typical symptom of diabetes. 2. Dizziness: When diabetic patients have poor blood sugar control, high blood sugar will lead to increased osmotic pressure in the brain, thus causing symptoms such as dizziness. 3. Lack of energy: Diabetic patients with relative or absolute lack of insulin, glucose can not be effectively utilized, and at the same time, protein and fat consumption increases, which can cause lack of energy and other discomforts. In addition to the above symptoms, patients with complications may also experience nausea, vomiting, blurred vision, numbness at the end of the limbs and other symptoms. People who suspect diabetes are advised to seek medical attention to clarify the situation.