Gestational Glucose Tolerance (Diagnostic)

Gestational Glucose Tolerance (Diagnostic)

Number
	102004
CPT
	82951; 82952
Related Information
	Endocrine Appendix
Synonyms
	Glucose Tolerance, Gestational ; O'Sullivan Diagnostic Replaced by Recommendations From the Fourth International Workshop-Conference
Test Includes
	100-g glucose load; plasma glucose measured fasting, and at 1, 2, and 3 hours
Special Instructions
	See the Endocrine Appendix for further information regarding glucose tolerance testing.
Specimen
	Serum or plasma
Volume
	2 mL
Minimum Volume
	0.5 mL serum, 1 mL plasma
Container
	Gel-barrier tube or gray-top (sodium fluoride/potassium oxalate) tube (separate blood within 45 minutes of collection)
Collection
	Draw a fasting blood sugar before administering 100-g glucose, and draw blood at 1, 2, and 3 hours. The subject should remain seated and not smoke throughout the test. Separate serum or plasma from cells within 45 minutes of collection.
Storage Instructions
	Maintain specimen at room temperature.
Patient Preparation
	For 3 days prior to the test, patients should eat an unrestricted diet of 150 or more grams of carbohydrate and be permitted unrestricted physical activity. Patients should be instructed to eat and drink nothing except water for at least 8 hours and not more than 14 hours before the test. Patients should also be advised to discontinue, whenever possible, all nonessential medication that can affect glucose metabolism at least 3 days before testing.
Causes for Rejection
	Improper labeling
Reference Interval
	See the Endocrine Appendix for further information regarding glucose tolerance testing.
Use
	Diagnose gestational diabetes
Methodology
	Enzymatic
Contraindications
	Patient with known history of diabetes mellitus
Additional Information
	Classification after pregnancy should include a postpartum evaluation with a 75-g, 2-hour oral glucose tolerance test [test 101675]. Women diagnosed with GDM should, in subsequent pregnancies, be reevaluated.
References
	Lind T, Phillips PR, and the Diabetic Pregnancy Study Group of the European Association for the Study of Diabetes, “Influence of Pregnancy on the 75-g OGTT, A Prospective Multicenter Study,” Diabetes, 1991, 40(Suppl 2):8-13. Magee MS, Walden CE, Benedetti TJ, et al, “Influence of Diagnostic Criteria on the Incidence of Gestational Diabetes and Perinatal Morbidity,” JAMA, 1993, 269(5):609-15. Metzger BE and Coustan DR, “Summary and Recommendations of the Fourth International Workshop-Conference on Gestational Diabetes Mellitus,” Diabetes Care, 1998, 21(Suppl 2):B161-7. “National Diabetes Data Group: Classification and Diagnosis of Diabetes Mellitus and Other Categories of Glucose Intolerance,” Diabetes, 1979, 28(12):1039-57. “Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus,” Diabetes Care, 1997, 20(7):1183-97.