[Diagnostic criteria for gestational diabetes mellitus]

To answer two questions: is there a threshold for pathological hyperglycemia after 24 weeks of gestation? What are the diagnostic criteria for gestational diabetes mellitus?

Review of the literature considering the relationships between glucose values and complications during pregnancy in women without specific care for this condition. Only the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study meets sufficient quality criteria.

Increasing glucose values during pregnancy, either at fasting and after a 75-g oral glucose-tolerance test, are independently associated with adverse pregnancy outcomes, especially birth weight above the 90th percentile for gestational age, caesarian delivery and fetal hyperinsulinemia. There is no obvious threshold at which risks increase. The International Association of Diabetes Pregnancy Study Group has proposed, considering the glycemic values associated with a 1.75-fold increased risk of macrosomia, fetal hyperinsulinism and adiposity in the HAPO study, the following criteria: fasting plasma glucose ≥ 0.92 g/L (5.1 mmol/L) and/or 1-hour plasma glucose value ≥ 1.80 g/L (10.0 mmol/L) and/or 2-hour plasma glucose value ≥ 1.53 g/L (8.5 mmol/L).

Choosing glycemic threshold to define gestational diabetes mellitus is necessarily arbitrary because of a continuum. Only experts may propose definition criteria.