The cortisone glucose tolerance test (cortisone GTT) combines administration of a carbohydrate challenge with a cortisone challenge. Cortisone enhances the synthesis of glucose from amino acids and fatty acids (gluconeogenesis) and, when administered with a glucose load, may produce an abnormal GTT that would not otherwise be evident. The cortisone GTT is used only in certain clinical situations and for research purposes.

• The reference values are similar to those for the OGTT except that the blood glucose level at the 2-hour interval may be 20 mg/dL higher than the client's fasting level.

• Those factors that may alter the results of an OGTT may also alter the results of a cortisone GTT.
• Failure to administer or take the oral cortisone as prescribed for the test will alter results.

• Inconclusive results of OGTT when prediabetes or "borderline" diabetes is suspected, with a 2-hour level of greater than 165 mg/dL considered indicative of diabetes

Nursing Care Before the Procedure

Client preparation is essentially the same as that for the OGTT.

• In addition, the client should be instructed on the purpose and administration of the oral cortisone acetate.

The procedure is the same as that for the OGTT except that cortisone acetate is administered orally 8 hours and again 2 hours before the standard GTT is begun.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for the OGTT.