According to the American Diabetes Association, the standard fasting plasma sugar level for diagnosing diabetes mellitus is:

The standard fasting plasma glucose level for diagnosing diabetes mellitus, as outlined by the American Diabetes Association (ADA), is indeed 126 mg/dl or higher. This threshold is critical for the proper identification of diabetes, as levels at or above this mark indicate that the body is not effectively regulating blood sugar, which is a hallmark of diabetes mellitus.

Fasting plasma glucose testing is recommended to be conducted after an overnight fast, and this measure is part of a broader set of criteria to diagnose diabetes. The threshold of 126 mg/dl is established based on research that correlates this level with a significantly increased risk of developing complications associated with diabetes, thus ensuring early identification and intervention can take place.