OBJECTIVE: To evaluate the diagnosis of gestational diabetes based on a 50-
g, one-hour glucose screening test result greater than or equal to 200 mg/d
L.
STUDY DESIGN: Retrospective ascertainment of pregnant women who had a 50-g,
one-hour glucose screening test result greater than or equal to 200 mg/dL
was performed among prenatal care registrants. The diagnosis of gestational
diabetes was determined by 100-g, three-hour oval 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 greater than or equal to 200 mg/dL. Four women could no
t be classified, two had pregestational glucose intolerance and four charts
were unavailable. Of the remaining 59 women, 11 (19%) had normal three-hou
r GTTs, and 48 (81%) were diagnosed with gestational diabetes (35 [59%], A(
1); 13 [22 %], A(2)). There was one large-for-gestational-age (LGA) infant
born in the nondiabetic group (9%), 13 LGA infants born in the A(1) group (
37%) and 6 LGA infants born to the A(2) diabetics (46%). The relationship b
etween maternal diagnosis and LGA outcome was statistically significant.
CONCLUSION A 50-g screening test result greater than or equal to 200 mg/dL
is not diagnostic of gestational diabetes. Nearly one of five such women ha
d a normal three-hour oral GTT Overdiagnosis of gestational diabetes may le
ad to unnecessary pregnancy surveillance and intervention.