The insulin tolerance test examines pituitary and adrenal function by injecting insulin into a patient's vein to lower their blood sugar level. It involves fasting overnight, having normal ECG and weight recorded, then a fixed dose of insulin is injected and the patient is monitored for 20-40 minutes. A normal cortisol response is above 550 nmol/L while levels below 550 nmol/L indicate impaired response requiring treatment. Growth hormone should rise above 20 mU/L. Side effects include sweating, palpitations and potential loss of consciousness so those over 60, with heart issues, or hormone disorders cannot have the test.