Blood glucose measurement is of great significance for patients with diabetes to understand the changes in blood glucose and the fluctuations of blood glucose. Patients who are hospitalized can measure 5-point blood glucose or even 7-point blood glucose, where 7-point blood glucose includes blood glucose before three meals and two hours after three meals, as well as before going to bed and at 3:00 a.m. The main purpose of measuring the 3:00 a.m. blood sugar is to identify what the cause of high fasting blood sugar is. If the blood sugar at 3 am is high and fasting is also high, it indicates that the dose of basal insulin is not enough, so you can increase the dose of basal insulin and press the blood sugar down again. If the blood sugar at 3:00 a.m. is low and hypoglycemia occurs, the fasting blood sugar is high, suggesting rebound hyperglycemia after hypoglycemia, suggesting that the basal insulin dose should be reduced. If the blood glucose at 3 am is normal, 5-7 mmol/L, within the acceptable range, and the fasting one is very high, it suggests that the person is affected by the secretion of growth hormone and cortisol.