The normal value of fasting blood glucose is 3.9-6.1mmol/L. Diabetes is not necessarily diabetes when it is greater than 5.6mmol/L, and it needs to be diagnosed in combination with postprandial blood glucose and other indicators. Typical symptoms of diabetic patients are “three more and one less”, i.e. drinking more, eating more, urinating more and losing weight. If the fasting blood glucose exceeds 7.0mmol/L, or the random blood glucose exceeds 11.1mmol/L, or the blood glucose 2 hours after meal exceeds 11.1mmol/L, and at the same time, the symptoms of diabetes, the diagnosis of diabetes can be confirmed. Fasting blood glucose between 3.9 and 6.1 mmol/L is normal. If the fasting blood glucose is more than 5.6mmol/L, the related examination can be improved. If ogtt test fasting blood glucose 6.1～6.9mmol/L, 2 hours blood glucose is normal, for the impaired regulation of fasting blood glucose, does not meet the diagnostic criteria for diabetes, belongs to pre-diabetes. Fasting blood glucose is greater than 5.6mmol/L, not necessarily diabetes, it is recommended to visit the hospital, improve the examination, a clear diagnosis.