What are the blood sugar levels for diabetes?

The blood sugar level that indicates diabetes depends upon the test used. With a fasting plasma-glucose test, results over 126 milligrams per deciliter suggest diabetes, according to WebMD. Levels over 200 show diabetes in an oral glucose-tolerance test or a randomly checked blood sugar level.

Prior to a plasma-glucose test, the patient must fast for 8 hours, WebMD reports. Then a blood sample is sent to a lab for analysis. Typically, diabetes is not diagnosed until two separate tests yield high results. The oral glucose-tolerance test also requires an 8-hour fast. A specific sugary drink is consumed, and blood is drawn 2 hours later. If an individual shows high blood sugar levels on a random test along with increased urination, thirst or weight loss, diabetes is suspected.