Final answer:
This question involves understanding the diagnostic criteria for diabetes mellitus using fasting blood glucose levels and the oral glucose tolerance test, as well as interpreting patient blood glucose data in the context of diabetes.
Step-by-step explanation:
The subject of this question pertains to the diagnosis of diabetes mellitus using various blood glucose tests, more specifically the fasting blood glucose (FBG) levels and the oral glucose tolerance test (OGTT). These diagnostic tests are critical in assessing whether an individual has normal glucose metabolism or diabetes.
A fasting blood glucose level greater than 125 mg/dL on two separate occasions often indicates diabetes. The OGTT involves the patient fasting for at least 12 hours, ingesting a 75g glucose solution, and then having their blood glucose measured 2 hours later. A level higher than 200 mg/dL at this time suggests diabetes. Symptoms combined with any random glucose level greater than 200 mg/dL also point towards a diabetic condition.
It's important to note that normal glucose tolerance, as indicated by Graph-A, shows a blood glucose peak and return to normal levels within a few hours post-ingestion of glucose. In contrast, diabetic patients, as indicated by Graph-B, exhibit higher than normal glucose levels that do not return to normal even after 2.5 hours. This indicates an intolerance to glucose, which is a hallmark of diabetes mellitus.