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Lowered Insulin Requirements in Late Stage Pregnancy and Placental Complications

A fall in insulin dose requirement in patients with preexisting diabetes can lead to increased risk of placental dysfunction…

Women with preexisting diabetes typically experience an increased need for insulin during the later stages of pregnancy due to an increase in insulin resistance during this time. A drop in insulin need late in pregnancy is often associated with placental complications. Previous studies have not shown a clear association between falling insulin requirements and placental compromise. Previous studies have also never included type 2 diabetes patients when examining this possible association.

This retrospective study followed 139 pregnancies with preexisting type 1, type 2 or overt diabetes to examine the association between falling insulin needs late in pregnancy and placental complications. The primary outcome for this study was a composite on clinical outcomes associated with placental dysfunction that included preeclampsia, small for gestational age, preterm delivery and placental abruption. Cohorts were grouped into either a case or control group depending on their insulin requirement. Case subjects saw their insulin requirement fall greater than 15% while control subjects never had requirements fall more than 15%.

Of the 139 pregnancies followed in this study, 35 met the requirements to be considered case subjects while the other 104 were control subjects. Results showed an increased risk for placental dysfunction determined by the composite of clinical markers in the mothers with falling insulin requirements (OR 4.4, 95% CI 1.73-11.26, P=0.002). Risk of preeclampsia was also greater in this group (OR 3.47, 95%CI 1.1-11.8, P=0.045).

While the majority of subjects in this study required increased insulin during the later stages of pregnancy, those with decreased insulin needs showed an increased risk for placental dysfunction, including preeclampsia. The infants born to mothers with a decreased insulin requirement were more likely to be small for gestational age, delivered earlier and required NICU admission compared to the infants born to control subjects. More studies are warranted to determine if similar results can be recorded, particularly with the inclusion of patients with type 2 diabetes.

Practice Pearls:

  • Typically patients with preexisting diabetes see an increased need for insulin during the late stages of pregnancy.
  • Those with reduced insulin needs in the later stages were often associated with adverse obstetric outcomes including placental insufficiency.
  • The results of this study showed that patients with a lowered insulin requirement during the later stages of pregnancy were at increased risk for placental complications, including preeclampsia.


Padmanabhan S, McLean M and Cheung NW. Falling Insulin Requirements are Associated With Adverse Obstetric Outcomes in Women With Preexisting Diabetes. Diabetes Care. October 2014.