Impaired glucose tolerance is defined as two-hour glucose levels of 140 to 199 mg per dL on 75 gram oral glucose tolerance test. It is said to be impaired glucose tolerance when there is raise of glucose level after 2 hours, but if it is less it is said to be type 2 diabetes mellitus. The fasting glucose may be either or mildly elevated.

The risk of progression to diabetes and development of cardiovascular disease is greater than for impaired fasting glycemia. Life style modifications in the person with impaired glucose tolerance help to prevent diabetes.

Impaired glucose tolerance stands between normalcy and diabetes. While in impaired glucose tolerance test the response to 75 gm glucose load is higher than the normal. In impaired glucose tolerance and diabetes, also referred to as prediabetes. In impaired glucose tolerance the levels of blood glucose are between normal and diabetic. People with IGI develop diabetes. Weight loss and exercise may help people with IGT to return to the normal glucose levels.

Impaired glucose tolerance test may be associated with following conditions:

• Acromegaly
• Chronic pancreatitis
• Cushing’s syndrome
• Gestational diabetes
• Gigantism
• Hyperparathyroidism
• Hyperprolactinemia
• Hyperthyroidism
• Insulin resistance
• Metabolic syndrome
• Polycystic ovary syndrome
• Primary hyperaldosteronism
• Prolactinoma.