[1] When used for assessing the integrity of the hypothalamic–pituitary–adrenal axis (HPA), insulin injections are continued to the point of inducing extreme hypoglycemia below 2.2 mmol/L (40 mg/dL).
It is assumed that the ability to respond to insulin-induced hypoglycemia translates into appropriate cortisol rise in the stressful event of acute illness or major surgery.
[4] The extreme hypoglycemic version of the ITT is potentially very dangerous and must be undertaken with great care, because it can iatrogenically induce the equivalent of a diabetic coma.
Side effects include sweating, palpitations, loss of consciousness and rarely convulsions due to severe hypoglycemia which may cause coma.
Patients with impaired cortisol responses (less than 550 but greater than 400 nmol/L) may only need steroid cover for major illnesses or stresses.