title: Is the 50-gram glucose screening test ever diagnostic?
abstract: The standard criteria for the diagnosis of gestational diabetes (GDM) is based on two abnormal values of a 3-h-100-g oral glucose tolerance test (GTT). Although a markedly elevated 1 h-50-g screen value has been suggested to support a diagnosis of GDM, limited data are available to substantiate this empiric observation. Our purpose was to examine the utility of various 50-g screen cutoff values in establishing the diagnosis of gestational diabetes. We identified 422 gravidas with a positive 50-g screen (> or = 135 mg/dl) who underwent additional glucose testing. GDM was defined according to the National Diabetes Data Group (NDDG) standards for the 3-h GTT. An analysis employing the criteria of Carpenter and Coustan was performed for comparison. If a patient had an elevated 50-g value and no 3-h GTT was performed, a fasting serum glucose > or = 140 mg/ dl was considered evidence of gestational diabetes. One hundred twenty four (29.4%) had GDM as defined by the NDDG criteria; this increased to 161 (38%) when the diagnosis was based on Carpenter and Coustan's criteria. The mean (+/- SD) gestational age at screening was 24 +/- 7 weeks. As expected, the prevalence of GDM increased in relation to an increasing 50-g value. All subjects with a 50-g screen > 216 mg/dl had evidence of gestational diabetes and required insulin for glycemic control. Patients with a 50-g screen > or = 220 mg/dl do not all require a 3-h GTT. Those with a fasting serum glucose of > or = 140 mg/dl may begin diet therapy, glucose monitoring, and insulin as indicated. If the fasting serum glucose is < 140 mg/dl, a 3-h GTT should be performed for confirmation of GDM. This approach will facilitate rapid therapeutic intervention and reduce the cost of care in this subset of patients. Gravidas with a very high 50-g screen are at significant risk of requiring insulin to maintain euglycemia during pregnancy.
authors.affiliation: Department of Obstetrics and Gynecology, Hutzel Hospital/Wayne State University, Detroit, MI 48201, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Bobrowski
authors.forename: S F
authors.initials: SF
authors.lastname: Bottoms
authors.forename: J A
authors.initials: JA
authors.lastname: Micallef
authors.forename: M P
authors.initials: MP
authors.lastname: Dombrowski
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000008:administration & dosage*; D005951:Glucose Tolerance Test / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D011247:Pregnancy; D011254:Pregnancy in Diabetics / Q000175:diagnosis*; D012372:ROC Curve
chemical_list: D001786:Blood Glucose; D005947:Glucose