Keywords
cord blood glucose - fetal blood glucose - hypoglycemia - infant of diabetic mother
- infant - newborn - peripartum period
Case Report
Infants born to mothers with diabetes (IDMs) frequently experience hypoglycemia soon
after birth, a condition that can lead to brain injury, especially if left untreated.
IDMs experience cessation of excessive glucose supply following birth. Due to beta-cell
hyperplasia and hyperinsulinemia developed during fetal life and downregulated gluconeogenesis,
the glucose levels in IDM rapidly drop after birth. The brain is primarily affected
by hypoglycemia due to its dependence on glucose as an exclusive energy source.
The fetal benefits of glucose control throughout pregnancy are supported by robust
research data. Some mothers never achieve diabetes control during pregnancy. In mothers
with poorly controlled diabetes in pregnancy, tight peripartum control of glucose,
usually with intravenous insulin,[1] is recommended. This is a common practice despite contentious conclusions in a systematic
review[2] and calls for less aggressive management prior to expected labor.[3] There is no research or even concern regarding adverse fetal effects following rapid
normalization of maternal glucose levels. However, it is plausible that following
fast maternal glucose normalization, the fetal glucose metabolism becomes similar
to that upon birth: rapid decrease of glucose supply coupled with hyperinsulinemia
and insufficient gluconeogenesis, leading to fetal hypoglycemia. Fetal hypoglycemia
is expected to result in the same consequences as in a neonate but in a setting with
no diagnostic opportunities and few to no options for intervention if it is suspected.
The literature lacks data regarding the fetal effects of stringent peripartum glycemic
control. The studies of peripartum glucose control were focused on neonatal hypoglycemia
and followed current recommendations for neonatal glucose testing. It was tested an
hour or later following birth, when the fetal hypoglycemia may have subsided.[4] In a single study reporting umbilical cord glucose levels in IDMs, the details of
maternal glycemic control are unclear.[5]
We report a case of an infant born at the 37th week of pregnancy to a mother with
poorly controlled type 2 diabetes throughout pregnancy. The mother's glucose level
was normalized with an intravenous insulin drip within 24 hours prior to cesarean
section delivery. The fetal whole blood glucose level, tested in the arterial cord
blood immediately after birth, was 2.1 mmol/L—significantly below the 5th percentile
for normal newborns (3.5 mmol/L)[6] and the World Health Organization neonatal hypoglycemia treatment threshold (2.6
mmol/L). Because of hypoglycemia and mild transitory tachypnea of the newborn, the
infant was admitted to the neonatal intensive care unit (NICU). The tachypnea resolved
within a few hours. The hypoglycemia was successfully managed with intravenous dextrose
once, followed by feeding. The infant had to receive supplemental feeding via an orogastric
tube for the first week of life and was discharged on the 8th day of life. No neurological
abnormalities were noted during the NICU stay. There is no follow up data.
This case highlights the potential for fetal hypoglycemia following the rapid normalization
of glucose levels in a diabetic mother. It is prudent to infer that in the patient
presented here, fetal hypoglycemia was more severe immediately following normalization
of maternal glucose than it was at birth. In this patient, the fetal beta cell hyperplasia
was moderate, considering moderately elevated maternal hemoglobin HbA1c
(7.9%) and mean glucose (9.8 mmol/L) prior to the labor. In the situations of severe
fetal beta-isle hyperplasia and/or maternal iatrogenic hypoglycemia, the fetal hypoglycemia
is anticipated to be more profound.
Fetal hypoglycemia might elucidate the recent findings of typical hypoglycemic brain
damage in children with no history of neonatal hypoglycemia.[7]
This hypothesis, supported by observation, suggests a need for a thorough clinical
study to evaluate the fetal, neonatal, and long-term consequences of tight peripartum
glycemic control. Additionally, early glucose monitoring in cord blood might facilitate
the timely identification and treatment of hypoglycemia in this subgroup of IDM.
