Does Insulin Treatment Affect Umbilical Artery Doppler Indices in Pregnancies Complicated by Gestational Diabetes?

Background/Objectives: Gestational diabetes mellitus (GDM) is one of the most common morbidities of pregnancy. The impact of increased maternal blood glucose on fetoplacental hemodynamics is not fully elucidated, especially in patients with uncontrolled GDM necessitating insulin therapy. The objective of this study was to assess the impact of insulin therapy on the umbilical artery dopplers in GDM pregnancies adequate for gestational-age fetuses. Methods: Retrospective observational study among 447 GDM pregnant women, divided according to their treatment (nutritional therapy (NT), long acting (LA) insulin, combined insulin) and 100 healthy controls with the same gestational age. The umbilical artery pulsatility index (UA-PI) was recorded at 28, 32 and 36 weeks. Results: UA-PI values declined in both GDM and healthy controls at all three time intervals. The combined insulin group showed reduced UA-PI values in comparison to the LA insulin group, but the difference never reached statistical significance. The combined insulin group exhibited significantly reduced UA-PI values at 32- and 36-weeks' gestation compared to the NT groups. Conclusions: A decreased impedance to blood flow in the umbilical artery of diabetic mothers on insulin therapy was observed. This was more pronounced during the last trimester. The extent to which umbilical artery PI can predict unfavorable outcomes has yet to be determined. Further additional studies are necessary to confirm the precise impact of glucose levels and medical interventions on the circulation of both the fetus and the mother.