Fasting blood glucose generally refers to the blood glucose measured by fasting on water for 8 to 10 hours the night before, and the test of blood glucose after 14 hours of fasting may be inaccurate, and care needs to be taken to avoid prolonged fasting so as not to cause the occurrence of hypoglycemia. Fasting blood glucose test is very meaningful for the evaluation of human blood glucose control, normal people with fasting blood glucose less than 2.8mmol/L, considered hypoglycemia, in 3.9mmol/L to 6.1mmol/L belongs to the normal range. Fasting blood glucose 6.1 to 7.0mmol/L, at the same time 2 hours after meal blood glucose <7.8mmol/L belongs to the impaired fasting blood glucose. Fasting blood glucose ≥7.0mmol/L, combined with symptoms of excessive drinking, polyuria, polyphagia, and weight loss are considered to be diagnosed as diabetes mellitus. Abnormal fasting blood glucose needs to go to the hospital in time to improve the relevant examination, clear diagnosis, and treatment under the guidance of the doctor.