What fasting plasma glucose level is diagnostic for diabetes?

A fasting plasma glucose level of 126 mg/dL or higher is diagnostic for diabetes mellitus. This threshold is based on guidelines established by organizations such as the American Diabetes Association. In the context of diabetes diagnosis, a fasting plasma glucose test measures blood sugar levels after an overnight fast. A level at or above 126 mg/dL indicates that the body is not effectively regulating glucose, which is a hallmark of diabetes.

To provide context for the other levels: a fasting glucose level of 100 mg/dL typically indicates normal blood glucose levels, while levels between 100 and 125 mg/dL suggest a state known as prediabetes. A level of 140 mg/dL or higher is indicative of diabetes during an oral glucose tolerance test rather than a fasting test. Therefore, the level of 126 mg/dL is the key value that confirms a diabetes diagnosis.