Answer- Case study- Gestational Diabetes Mellitus and Neonatal hypoglycemia-A patient who had gestational diabetes has just delivered …

A patient who had gestational diabetes has just delivered a 10 lb baby. The baby appears “jittery” and heel stick glucose is 30 mg/dL. Which of the following mechanisms is the explanation for the newborn’s hypoglycemia?

A. The mother’s relative hyperinsulinemia

B. The baby’s relative hyperinsulinemia

C. The mother’s hyperglycemia

D. The baby’s hyperglycemia

E. Placental insulin production

Answer- The correct answer is- B- The baby’s relative hyperinsulinemia.

Gestational diabetes is a condition characterized by high blood glucose levels that is first recognized during pregnancy. The condition occurs in approximately 4% of all pregnancies.

Almost all women have some degree of impaired glucose tolerance as a result of hormonal changes that occur during pregnancy. That means their blood sugar may be higher than normal, but not high enough to cause diabetes. During the later part of pregnancy (the third trimester), these hormonal changes place pregnant woman at risk for gestational diabetes.

During pregnancy, increased levels of certain hormones made in the placenta help shift nutrients from the mother to the developing fetus. The counter regulatory hormones are produced by the placenta to help prevent the mother from developing low blood sugar(figure). They work by resisting the actions of insulin.



Figure- – Mechanism of gestational diabetes

Over the course of the pregnancy, these hormones lead to progressive impaired glucose tolerance (higher blood sugar levels) that means for a given glucose load larger amount of insulin is required.

Usually, the mother’s pancreas is able to produce more insulin (about three times the normal amount) to overcome the effect of the pregnancy hormones on blood sugar levels. If, however, the pancreas cannot produce enough insulin, blood sugar levels will rise, resulting in gestational diabetes.

Now in gestational diabetes, the fetus is oversupplied with glucose from the mother causing the fetal pancreas to overproduce insulin. At delivery, the glucose supply from the mother is suddenly terminated and the relative hyperinsulinemia of the baby causes hypoglycemia until the baby’s body can adjust to this new environment by decreasing insulin release and increasing glucose release. Hypoglycemia in the first few hours of the newborn’s life is a common complication of gestational diabetes.

Newborn hyperglycemia cannot give a heel stick of 30 mg/dL of glucose. The placenta does not make insulin and the insulin molecule cannot cross the placenta, so the mother’s relative hyperinsulinemia is not the cause of this problem. While the mother’s hyperglycemia has led to the baby’s relative hyperinsulinemia, the mother’s blood glucose levels do not cause the drop in the baby’s blood glucose levels after birth.

Hence the correct answer is Baby’s relative hyperinsulinemia.

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