We have compared the characteristics of those screened and unscreened for g
estational diabetes mellitus (GDM) in a multiethnic population in New Zeala
nd. All obstetric records for a 12-month period were reviewed manually and
electronically. Pre-gestational diabetes status, screening for GDM and obst
etric history were recorded. Data for 4885 singleton pregnancies, uncomplic
ated by known pre;existing diabetes were available. Overall 50.6% of women
were screened for GDM using a glucose challenge test, ranging between 36.8%
among Europeans to 68.5% among Pacific Islanders (P < 0.001). Attendance a
t a follow up oral glucose tolerance test among those with a positive scree
n was 77.4%, with no ethnic difference. Rates of GDM were 3.3, 7.9 and 8.1%
for Europeans, Maori and Pacific Islanders. An estimated 45-72% of women w
ith GDM went undetected. Although increasing weight was associated with an
increased likelihood of screening, 44.9, 34.8 and 21.1% of obese (weight 85
+ kg) Europeans, Maori and Pacific Islanders, respectively, were not scree
ned. Increasing age was not associated with increased screening. Screening
for GDM is not occurring even in those with clear and agreed indications fo
r selective screening. We hypothesise that the current debate over criteria
for selective screening may be undermining screening for those most at ris
k. (C) 2000 Published by Elsevier Science Ireland Ltd. All rights reserved.