Glucosa Metabolism Disorders

Diagnosis and Definition

The American Diabetes Association defines impaired glucose tolerance (IGT) as a state characterized by blood glucose levels of 140-199 mg/dL (7.8-11.0 mmol/L) 2 hours after a 75g oral glucose tolerance test 1.
Impaired glucose tolerance, also known as "altered glucose tolerance", represents a pre-diabetic state where the body cannot process glucose properly, but levels are not high enough to diagnose diabetes, according to the American Diabetes Association 2.

Insulin resistance can exist even in states of normoglycemia and precedes the development of glucose alterations, as stated by the Endocrine Society 3.

Impaired glucose tolerance is a clinical manifestation that can result from insulin resistance combined with insufficient insulin secretion, as reported by the Infectious Diseases Society of America and the American Diabetes Association 4, 5.
Insulin resistance is an underlying mechanism that can lead to impaired glucose tolerance when insulin secretion is insufficient to compensate for such resistance, according to the American Diabetes Association 2, 5.

The progression from insulin resistance to impaired glucose tolerance and eventually to type 2 diabetes occurs when pancreatic beta-cell function deteriorates significantly, as noted by the American Diabetes Association 5.