Final answer:
Impaired glucose tolerance (IGT) is assessed through a glucose tolerance test (GTT), in which elevated blood glucose levels that do not normalize within 2.5 hours indicate glucose intolerance. Further tests like the Insulin Tolerance Test (ITT) and Glucagon Tolerance Test (GuTT) differentiate between types of diabetes. Graph interpretation of GTT results helps in diagnosing diabetes.
Step-by-step explanation:
Criteria for Impaired Glucose Intolerance
Impaired glucose tolerance (IGT) is a condition characterized by higher than normal blood glucose levels after eating, but not high enough to be classified as diabetes. The criteria for IGT are based on the results of a glucose tolerance test (GTT). This test involves a fasting period, after which the patient consumes a glucose solution, and subsequent blood glucose level measurements are taken at intervals to assess the body's ability to manage glucose. If blood glucose levels rise sharply and fail to return to normal within 2.5 hours after ingestion, the patient is considered glucose intolerant, which is a characteristic of type 2 diabetes. To confirm the type of diabetes, further tests like the Insulin Tolerance Test (ITT) and Glucagon Tolerance Test (GuTT) may be conducted.
In the case of ITT, hypoglycemia relative to the initial blood glucose level indicates Insulin Dependent Diabetes Mellitus (IDDM). In the GuTT, hyperglycemia suggests defective insulin receptors, while no change indicates excessive insulin antagonists. Increasing age also affects glucose metabolism, contributing to higher levels of blood glucose and decreased insulin sensitivity, prevalent among elderly populations.
Graph interpretation of GTT results also plays a crucial role. A steep rise in blood glucose after a half hour that does not normalize even by 2.5 hours post-glucose ingestion is indicative of diabetes. IGT is part of the spectrum of hyperglycemia and often precedes the development of type 2 diabetes, a multifactorial disorder characterized by insulin resistance and impaired insulin production leading to high blood glucose levels.