Final answer:
Evaluating fasting hypoglycemia in a non-diabetic patient involves different tolerance tests to understand how the body manages blood glucose levels, with particular attention to responses after fasting, glucose ingestion, and hormone administration.
Step-by-step explanation:
The assessment of fasting hypoglycemia in a patient without diabetes mellitus involves various diagnostic tests to determine the body's ability to regulate blood glucose levels. In a glucose tolerance test (GTT), if a patient's fasting blood glucose level is normal or slightly elevated but does not return to normal within 2½ hours after glucose ingestion, this may indicate diabetes mellitus. However, for hypoglycemia, the key is observing blood sugar levels in a fasting state and in response to certain stimuli such as meals or hormone injections.
Glucagon tolerance tests can indicate the cause of hypoglycemia by analyzing the blood glucose response. If hyperglycemia is seen, it indicates defective insulin receptors, while no change in blood glucose suggests excessive insulin antagonists. An insulin tolerance test reveals how the patient's insulin secretion responds to administration, which helps evaluate the presence of insulin-dependent diabetes mellitus (IDDM) or hypoglycemia due to other causes.