Question: what is high blood sugar when fasting?
Answer: A fasting blood sugar level from 100 to 125 mg/dL (5.6 to 6.9 mmol/L) is considered prediabetes. If it's 126 mg/dL (7 mmol/L) or higher on two separate tests, you have diabetes. Oral glucose tolerance test. For this test, you fast overnight, and the fasting blood sugar level is measured.