Objective: To determine factors possibly associated with early development of GDM (before 24 weeks of gestation)
Subjects: A total of 196 pregnant women who were at risk for GDM and started antenatal care at antenatal clinic before 24 weeks of gestation, Siriraj Hospital between January 2002 and December 2002 were enrolled. Those who were known cases of DM before pregnancy were excluded.
Method: Screening test with 50 g GCT was offered to all participants at their first visits and 100g OGTT was used as a diagnostic test. If GDM was not diagnosed, they were retested between 28-32 weeks using the same criteria. Early GDM was defined as the diagnosis of GDM before 24 weeks of gestation. Late GDM was defined as the diagnosis of GDM later than 24 weeks of gestation. Clinical risk factors of the 2 groups were
compared to determine the association with early development of GDM.
Results: Of 196 women with GDM, 127 (64.5%) were diagnosed before 24 weeks of gestation, and 69 (35.5%) were diagnosed later. Obesity was only one significant risk factor for early development of GDM. Early GDM group were more likely to be obese than late GDM group (20.5% and 8.7% respectively, p=0.042). Other clinical risks were not significantly different between the 2 groups. Early GDM were more likely to
diagnose if 3 or more clinical risk factors were found compared to late GDM group (8.75% and 2.9% respectively) but not significantly different.
Conclusion: Obese women (BMI >27 kg/m2) should attend the screening program at early pregnancy to reduce maternal complications and adverse neonatal outcomes.

Keywords: Clinical risk factors, Gestational diabetes mellitus, Early diagnosis