Gestational Diabetes One-hour Screen

Gestational Diabetes One-hour Screen

Number
	102277
CPT
	82950
Synonyms
	Gestational Diabetes Screen - Third International Workshop ; O'Sullivan screen replaced by recommendation from the Third International Workshop-Conference on Gestational Diabetes Melitus
Test Includes
	50-g 1-hour glucose tolerance challenge
Special Instructions
	Screening of patients at risk should be performed at the first prenatal visit. The patient need not be fasting. Most American obstetricians screen with a 50-gram oral glucose load followed by a plasma glucose determination one hour later. If the result is normal, screening should be repeated between 24 and 28 weeks of gestation. A glucose threshold after 50-gram load of >139 mg/dL identifies approximately 80% of women with gestational diabetes mellitus (GDM), while the sensitivity is further increased to approximately 90% by a threshold of >129 mg/dL. Perform a diagnostic 100-gram oral glucose tolerance test (OGTT) on a separate day in women whoexceed the chosen threshold on 50-gram screening. See the Endocrine Appendix for further information regarding glucose tolerance testing.
Specimen
	Serum or plasma
Volume
	2 mL
Minimum Volume
	1 mL (gray-top), 0.5 mL serum
Container
	Gray-top (sodium fluoride) tube, gel-barrier tube or red-top tube (separate blood within 45 minutes of venipuncture)
Collection
	Draw specimen 1 hour after a 50-g glucose challenge.
Storage Instructions
	Maintain specimen at room temperature.
Patient Preparation
	None; glucose challenge is administered without regard to time of day or time of last meal.
Causes for Rejection
	Improper specimen labeling
Reference Interval
	65-139 mg/dL
Critical Values
	<40 mg/dL or >140 mg/dL
Use
	Test for gestational diabetes
Limitations
	If the initial test is normal in an at-risk individual, it should be repeated between 24 and 28 weeks because carbohydrate tolerance decreases in the second half of pregnancy.
Methodology
	Enzymatic
Contraindications
	Patient with known history of diabetes mellitus
Additional Information
	According to ADA, a glucose threshold of >139 mg/dL after 50-gram load identifies approximately 80% of women with gestational diabetes mellitus, while the sensitivity is further increased to approximately 90% by a threshold of >129 mg/dL. A one-step approach is available for gestational diabetes mellitus (GDM) screening (may be performed in clinics with high prevalence of GDM): Perform a diagnostic 100-gram OGTT [test 102004] in all women to be tested at 24 to 28 weeks. A 50-gram one-hour glucose challenge at 24 to 28 weeks should preclude earlier testing depending on the circumstances. Patients with a positive test should be tested further with Gestational Glucose Tolerance [test 102004]. Classification after pregnancy should include a postpartum evaluation with a 75-gram two-hour oral glucose tolerance test [test 101675].
References
	American Diabetes Association, “Postpartum Follow-up of Women With Gestational Diabetes,” Medical Management of Pregnancy Complicated by Diabetes, Banks P, ed, Alexandria, VA: American Diabetes Association, 1993; 103-105. 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):609-615. Metzger BE and Coustan DR, “Summary and Recommendations of the Fourth International Workshop-Conference on Gestational Diabetes Mellitus,” Diabetes Care, 1998; 21(Suppl 2):B161-167. “National Diabetes Data Group: Classification and Diagnosis of Diabetes Mellitus and Other Categories of Glucose Intolerance,” Diabetes, 1979; 28(12):1039-1057. “Report of the Expert Committee on the Diagnosis and Classification of Diabetes Mellitus,” Diabetes Care, 1997; 20(7):1183-1197. "American Diabetes Association: Clinical Practice Recommendations," Diabetes Care, 2008;31(Suppl 1).