Insulin tolerance test

The unstimulated serum cortisol and rapid ACTH stimulation tests are useful in the diagnosis of adrenal crisis (Table 42-2). The insulin tolerance test is contraindicated owing to preexisting hypoglycemia. The metyrapone test is also contraindicated because metyrapone inhibits cortisol production. 

Drug/Lab test interactions These agents may produce hypoglycemia and interfere with glucose or insulin tolerance tests. Propranolol and betaxolol may interfere with the glaucoma screening test due to a reduction in intraocular pressure. 

Hypokalemia occurred in 29 children undergoing insulin tolerance tests the mean serum potassium concentration at the start was 4.1 mmol/1, falling to a mean of 3 mmol/1 at 30 minutes (108). Ten children had a serum potassium concentration below 2.9 mmol/1 and one had a concentration of 2.2 mmol/1. There were no cardiac events. 

An 8-year-old girl had an insulin tolerance test with 0.05IU/kg to assess growth hormone concentrations. The blood glucose concentration fell to 0.9 mmol/1 and she was given intravenous dextrose. She had a generalized seizure and developed ventricular flutter. 

Binder G, Bosk A, Gass M, Ranke MB, Heidemann PH. Insulin tolerance test causes hypokalaemia and can provoke cardiac arrhythmias. Hormone Res 2004 62 84-7. 

Key words Type II diabetes mellitus, drug discovery, glucose tolerance test, insulin tolerance test,... 

A series of 4-oxazoleacetic acid derivatives was identified as a group of potential hypoglycaemic agents in mice via the insulin tolerance test [197]. The most potent compound, AD-4610 (33), was found to potentiate biphasic glucose-induced insulin secretion in the perfused pancreas and in normal rats in a glucose-dependent fashion. AD-4610 also lowers plasma glucose in yellow KK mice, a model of NIDDM in which tolbutamide is inactive [198]. Development of AD-4610 and/or analogues is reported to have been discontinued [167]. 

Glipizide, 15 mg, potentiated insulin action and amplified plasma insulin response to meals more than glyburide, 15 mg, which improved insulin sensitivity, as assessed by an insulin-tolerance test, more than glyburide. The two agents both improved glucose control by 25% compared with placebo (Groop et al., 1985). 

BOX Sb-3 Protocol for the Insulin-Induced Hypoglycemia Stimulation T t -(Insulin Tolerance Test)... 

Penney R, Blizzard RM, Davis WT. Sequential arginine and insulin tolerance tests. J Clin Endocrinol Metab 1969 29 1499-501. 

The hypolhalmic-piiuiiary-adreno-cortical axis may be investigated by performing an insulin tolerance test (ITf). The details and hazards of this lest have been previously de.scribed (p. 77). 

The insulin tolerance test is used in diagnosis of pituitary insufficiency which may lead to secondary failure of the adrenal cortex. 

To confirm hypercortisolism, early morning urinary corlisohcreatinine ratios will be elevated, diurnal rhythm of serum cortisol will be absent, there will be no cortisol rise during an insulin-tolerance test, and serum cortisol will not suppress with a low dose of dexamethasone. 

This test is completely free from side effects and can be performed in conjunction with the TRH test and the insulin tolerance test, since there is no interaction between the various hormones released (MIO). This procedure provides a test of pituitary reserve of LH, FSH, TSH, PRL, GH, and ACTH. 

Clinically, in overweight people with DM2, Brynes et al. (2000) did not find an association with dietary fatty acid manipulations (MUFA, 20.3 3.5% energy versus PUFA, 13.4 1.3% energy) on insulin sensitivity, assessed by the short-insulin tolerance test. This study was limited by a small sample size (n = 9). 

---