The importance of declining insulin requirements during pregnancy in patients with pre-gestational gestational diabetes mellitus

ObjectiveIn patients with pre-gestational and gestational diabetes mellitus (GDM), insulin requirements often increase during the third trimester of pregnancy in order to maintain proper glycemic control. However, a fraction of patients demonstrate a significant decrease in insulin requirements in late gestation. We aimed to evaluate the clinical significance of decreasing insulin requirements in patients with pre-gestational diabetes and GDM with respect to fetal wellbeing and pregnancy outcome.Study designWe performed a retrospective cohort study in a single referral center for gestational diabetes between 1/2010 and 12/2014. Healthy pregnant women with pre-gestational diabetes and GDMA2 and a decrease of at least 30% in insulin requirements over a period of two weeks during the third trimester (group A) were compared to women with stable or increasing insulin requirements (group B). The primary outcome was a composite of situations associated with feto-placental dysfunction (fetal growth restriction, oligohydramnios and cesarean section due to category 2-3 monitor). Secondary outcomes were maternal oral glucose tolerance test (OGTT) results 6 weeks postpartum, neonatal intensive care unit (NICU) admission rates, Apgar scores ≤7 at 5 min, arterial blood pH ≤ 7.1, macrosomia, neonatal hypoglycemia and a composite adverse neonatal outcomes (defined as one or more of the following: respiratory morbidity, cerebral morbidity, phototherapy, need for blood transfusion, necrotizing enterocolitis or death).ResultsGroup A consisted of 101 women and group B − of 203 women. There were no differences between the groups in demographic characteristics or diagnostic characteristics of diabetes. The frequency of conditions related to feto-placental dysfunction did not differ between the groups (7.9% vs. 8.4%, p = 0.61). Secondary outcome measures also did not differ between the groups, regardless of insulin requirements.ConclusionDecreasing insulin requirements during the third trimester are not associated with adverse perinatal outcome related to placental dysfunction.