For people with undiagnosed diabetes, a four-hour post-lunch blood glucose of 6.6 mmol/L is high and abnormal; however, it is normal for people with diabetes, and is the standard for glycemic control. Clinically, fasting blood glucose and 2-hour postprandial blood glucose are often used as assessment indicators. The normal blood glucose four hours after lunch should be close to the fasting blood glucose level, i.e., 3.9~6.0mmol/L, so the blood glucose of 6.6mmol/L four hours after lunch is on the high side and not normal. It is recommended to improve the fasting blood glucose, 2-hour postprandial blood glucose, glycated hemoglobin and other related tests. For diabetic patients, the goal of glycemic control is generally 4.4mmol/L to 7.0mmol/L for fasting blood glucose, and not more than 10.0mmol/L for non-fasting blood glucose, so blood glucose of 6.6mmol/L four hours after lunch is a normal glycemic control goal. It is recommended to go to the hospital when abnormal blood glucose values occur.