Fasting blood glucose of 5.5 mmol/L is the normal range. In normal individuals, venous plasma glucose levels are 3.9-6.1 mmol/L in the fasting state. 6.1-6.9 mmol/L is impaired fasting glucose, which is considered prediabetes. If fasting plasma glucose is ≥7.0 mmol/L, diabetes should be considered. It should be noted that fasting is defined as not having eaten any calorie-containing food for at least 8 hours. Moreover, venous glucose should be used as the judgment criterion, and normal or abnormal fingertip glucose cannot be used as the diagnosis or exclusion criterion of diabetes mellitus. Besides, some diabetic patients may have normal fasting blood glucose, but their blood glucose has already started to rise after meals. Therefore, although fasting blood glucose 5.5mmol/L is normal blood glucose, in some high-risk people who have family history of diabetes or found diabetes during pregnancy, overweight, abdominal obesity, or more stressful, often stay up late, insomnia, etc., if you want to completely exclude abnormal blood glucose, it is recommended to go to the hospital to do a glucose tolerance test to look at fasting blood glucose, taking 75g of glucose 1 hour and 2 hours after taking glucose, respectively. If the blood glucose is within the normal range for all three times, then the blood glucose problem can be ruled out.