Falling insulin requirement in late pregnancy: association with obstetric and neonatal outcomes

To investigate whether diminishing insulin requirement in the third trimester is associated with placental dysfunction.

Two-year retrospective cohort study at one tertiary care center of women with pregestational or gestational diabetes, their insulin requirements, and complications associated with placental dysfunction.

Of 157 women, 21 (13%) experienced declining insulin requirement, with average decline of 28% at 34 weeks. They were more likely to have pregestational diabetes (71.4% vs. 42.6%; p < 0.01) and delivered earlier (median 36w4d vs. 37w4d; p < 0.01). There was no difference in placental dysfunction related complications (33% vs. 24%; p = 0.37). There was an increased rate of polyhydramnios (42.9% vs. 8.8%; p < 0.01). NICU admission (62% vs. 33%; p < 0.01) and neonatal respiratory distress (52% vs. 24%; p < 0.01) was higher in cases of declining insulin requirement independent of gestational age.

A decline in insulin requirement should raise concern for increased risk of NICU admission and neonatal respiratory distress.