Pregnant women checking fasting blood sugar the day before usually after 10 p.m., no longer eat, it is recommended to consult a doctor. Fasting blood glucose is one of the most important methods of diagnosing diabetes, which can reflect the function of pancreatic islet B cells. Usually fasting blood glucose measurement needs to be fasted for 8~10 hours, therefore, no more food is usually taken after ten o’clock in the evening the day before the check. Tight control of blood glucose during pregnancy is the main measure to improve the prognosis of mothers and children with gestational diabetes. Both average and fluctuating values of blood glucose should be controlled. The control goals are fasting blood glucose 3.9-5.8 mmol/L, preprandial blood glucose <5.6 mmol/L, 1-hour postprandial blood glucose <7.8 mmol/L, and 2-hour postprandial plasma blood glucose <6.7 mmol/L. If the fasting blood sugar of pregnant women is abnormal, it is recommended to go to the hospital in time to avoid delaying the condition.