High blood sugar generally has no early signs, most of the time when the blood sugar is high before the symptoms, when there is high blood sugar can be more drinking, eating, urinating and weight loss, as well as the complications of various systems and other symptoms. 1. Drinking, urinating, eating and weight loss: The increase of blood glucose concentration in the blood will make the plasma osmotic pressure increase, which will make a large amount of water loss, thus leading to polyuria, and excessive urinary output will lead to thirst, which will lead to polydipsia. Sugar loss patients appear polyphagia, fat and protein metabolism disorders, fat and protein consumption, resulting in weight loss. 2. Complications: prone to diabetic macrovascular lesions, such as cardiovascular and cerebrovascular disease, diabetic microvascular lesions, such as diabetic nephropathy, diabetic ophthalmopathy, and diabetic neuropathy. 3. Although there are no early signs of high blood glucose, there are some high-risk groups, such as age ≥ 40 years; abdominal obesity; first-degree relatives with a history of diabetes mellitus; history of delivery of giant babies or a history of gestational diabetes mellitus; a history of polycystic ovary syndrome in women; hypertension and hyperlipidemia people; a history of steroid use of the population and so on. It is recommended that people at high risk of diabetes should test their blood glucose regularly to recognize abnormal blood glucose status early for treatment.