What is the 2-hour glucose criteria for diagnosing diabetes mellitus after ingestion of 75 grams of glucose?

The criteria for diagnosing diabetes mellitus, specifically using the 2-hour glucose test after a 75-gram glucose load, is a key aspect of diabetes screening. A 2-hour plasma glucose level that is greater than or equal to 200 mg/dL signifies diabetes. This value indicates that the body's insulin response is inadequate for managing glucose levels following an artificial glucose challenge, which is indicative of diabetes mellitus.

The threshold of 200 mg/dL is significant because it delineates a clear point at which a diagnosis can confidently be made. Levels below this point, such as those in the ranges of 140 mg/dL or 160 mg/dL, do not meet the criteria for a diabetes diagnosis, and a level between 140-199 mg/dL indicates impaired glucose tolerance, rather than confirming diabetes. Therefore, identifying a 2-hour glucose level of 200 mg/dL or more is critical for the diagnosis of diabetes.