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

OBJECTIVE To investigate whether diminishing insulin requirement in the third trimester is associated with placental dysfunction. STUDY DESIGN 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. RESULTS 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. CONCLUSIONS A decline in insulin requirement should raise concern for increased risk of NICU admission and neonatal respiratory distress.