Fasting blood glucose 8mmol/L is high for both normal people and diabetics. 1. The normal value of fasting blood glucose for normal people is between 3.9~6.1mmol/L, so a high fasting blood glucose of 8mmol/L may be caused by diabetes, infection, stress, etc. It is recommended to consult a professional physician for a clear diagnosis. 2. For patients who have been diagnosed with diabetes in the past, the general fasting blood glucose needs to be controlled between 4.4~7.0mmol/L, so the fasting blood glucose of 8mmol/L is on the high side, which has not reached the control target, and professional doctors should be consulted to adjust the treatment program. Once the blood sugar level is found to be elevated, it is recommended to consult a doctor in time. Patients with abnormal blood glucose need to control their diet in their life, avoid large intake of food with high sugar content, exercise appropriately and monitor their blood glucose regularly.