Normal levels should be below 99 mg/dL. Pre-diabetes is diagnosed when levels are between 100 to 125 mg/dL. Diabetes is confirmed if your fasting blood glucose levels are 126 mg/dL or above on repeated tests. Random or nonfasting blood glucose levels of above 200 mg/dL could mean you have diabetes, as well.lucose is required by the body to maintain life. However, it is possible to have too much of a good thing. Hyperglycemia, or high blood glucose levels, may be due to diabetes, medications, stress, illness, hyperthyroidism, Cushing syndrome, pancreatitis or pancreatitis cancer.