What fasting glucose level is diagnostic for diabetes mellitus?

A fasting glucose level of greater than or equal to 126 mg/dL is diagnostic for diabetes mellitus. This threshold is established according to guidelines set by the American Diabetes Association (ADA). When testing for diabetes, a fasting plasma glucose test measures the blood sugar levels after an overnight fast. A level of 126 mg/dL or higher indicates that the body has insufficient insulin response or insulin resistance, leading to elevated glucose levels.

The significance of the 126 mg/dL cutoff is that it helps to identify individuals who may require further evaluation and potential management for diabetes. This diagnostic criterion plays a critical role in screening and diagnosing the disease early, which is essential for preventing complications associated with uncontrolled diabetes.

The other options represent glucose levels that fall within the normal or prediabetic range but do not meet the criteria for a diabetes diagnosis. Less than 100 mg/dL is considered normal, while a fasting glucose level between 100-125 mg/dL indicates prediabetes, a condition that raises the risk of developing type 2 diabetes but does not confirm the diagnosis. A level greater than 140 mg/dL is indicative of a hyperglycemic state but is not an established diagnostic criterion for diabetes specifically; it may suggest diabetes if found independently,