Gestational diabetes. Is a 50-g screening result > or = 200 mg/dL diagnostic?
OBJECTIVE
To evaluate the diagnosis of gestational diabetes based on a 50-g, one-hour glucose screening test result > or = 200 mg/dL.


METHODS
Retrospective ascertainment of pregnant women who had a 50-g, one-hour glucose screening test result > or = 200 mg/dL was performed among prenatal care registrants. The diagnosis of gestational diabetes was determined by 100-g, three-hour oral glucose tolerance test (GTT) results and/or repeated fasting serum glucose measures.


RESULTS
In 1995, 69 women were referred to the gestational diabetes clinic with a 50-g result > or = 200 mg/dL. Four women could not be classified, two had pregestational glucose intolerance and four charts were unavailable. Of the remaining 59 women, 11 (19%) had normal three-hour GTTs, and 48 (81%) were diagnosed with gestational diabetes (35 [59%], A1; 13 [22%], A2). There was one large-for-gestational-age (LGA) infant born in the nondiabetic group (9%), 13 LGA infants born in the A1 group (37%) and 6 LGA infants born to the A2 diabetics (46%). The relationship between maternal diagnosis and LGA outcome was statistically significant.


CONCLUSIONS
A 50-g screening test result > or = 200 mg/dL is not diagnostic of gestational diabetes. Nearly one of five such women had a normal three-hour oral GTT. Overdiagnosis of gestational diabetes may lead to unnecessary pregnancy surveillance and intervention.
Shivvers
S A
SA
Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas 75235-9032, USA.
Lucas
M J
MJ
D000328:Adult; D016640:Diabetes, Gestational / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D005951:Glucose Tolerance Test; D006801:Humans; D011237:Predictive Value of Tests; D011247:Pregnancy; D011295:Prenatal Care / Q000592:standards*; D012016:Reference Values