A normal fasting blood sugar result is lower than 100 milligrams of glucose per deciliter of blood (mg/dL).
What level suggests prediabetes?
If your fasting blood sugar level is 100 mg/dL to 125 mg/dL, you have impaired fasting glucose — commonly known as prediabetes. To confirm the diagnosis, your doctor may repeat the fasting blood sugar test several days to a week later.
What level suggests type 1 or type 2 diabetes?
A fasting blood sugar level of 126 mg/dL or higher is consistent with either type 1 or type 2 diabetes when accompanied by classic signs and symptoms of diabetes — increased thirst or hunger, frequent urination, weight loss or blurred vision.
To confirm the diagnosis, your doctor may repeat the fasting blood sugar test on another day. If your test results are 126 mg/dL or higher twice in a row after at least eight hours of fasting, you may have diabetes.
If your blood sugar level is higher than 200 mg/dL and you have signs or symptoms of diabetes, you may be diagnosed with diabetes without a second test for confirmation.