Reassessment of the new diagnostic thresholds for gestational diabetes mellitus: an opportunity for improvement
The diagnosis of gestational diabetes mellitus (GDM) has been based on guidelines derived from expert opinion. The original threshold blood glucose levels (BGLs) for diagnosis recommended by the Australian Diabetes in Pregnancy Society (ADIPS) had no scientific validity.1 Subsequently, intervention studies provided validity for these levels.2,3 However, these criteria remained statistically unsupported until the results of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study were published.
Assessment of the Hyperglycemia and Adverse Pregnancy Outcome study
HAPO analysed data from 23 316 women enrolled in a blinded epidemiological study where neonatal and maternal adverse events were assessed according to prespecified blood glucose ranges after a 75 g oral glucose tolerance test performed at 24–32 weeks of gestation.4 This study showed strong continuous relationships between fasting blood glucose (FBG) levels, 1-hour BGL and 2-hour BGL after a 75 g oral glucose tolerance test and outcomes. HAPO assessed different odds ratios (ORs) for risk of developing adverse neonatal outcomes for each BGL parameter and the percentage of women diagnosed. Subsequently, the International Association of Diabetes and Pregnancy Study Groups (IADPSG) reached consensus that the…