Gestational diabetes mellitus diagnosed by screening or symptoms: does it matter?

To investigate whether outcome differs between pregnancies complicated by gestational diabetes mellitus (GDM), which was either detected by risk-factor based screening when no clinical signs are apparent (screening-group) or due to clinical signs of hyperglycemia (e.g. accelerated fetal growth or hydramnios) (diagnosis-group).

A retrospective cohort of 249 patients with GDM treated between 2006 and 2009 were identified: 74 in the diagnosis-group and 175 in the screening-group. Fetal macrosomia was defined as an abdominal circumference (FAC) >90th percentile at the time of diagnosis of GDM. Large for gestational age (LGA) was defined as a birthweight >90th percentile, corrected for gestational age, parity and sex.

GDM was diagnosed 4 weeks later in the diagnosis-group. At diagnosis of GDM, more infants in the diagnosis-group had a FAC >p90 and at birth more infants in this group were LGA.

GDM diagnosed by screening is associated with a lower incidence of fetal and neonatal macrosomia than GDM diagnosed by clinical symptoms. A later diagnosis of GDM is more prevalent in presumed low-risk pregnancies. These results favour a policy of routine screening.