Insulin Secretion and Sensitivity

 

As you can see above, the graph on the left shows both women with gestational diabetes and women without gestational diabetes are able to secrete additional insulin. However, women with gestational diabetes cannot secrete enough insulin to keep their blood glucose in the target range.

The graph on the right illustrates that insulin sensitivity diminishes for both types of patients--those with gestational diabetes and those without.

 

Adverse Outcomes of GDM

Elevated HA1c is indicative of poor glycemic control & higher risk of adverse outcomes

 

HA1c is the marker for blood glucose control. Elevated readings indicate poor glycemic control, which is linked to a higher risk for adverse outcomes

 

HA1c is the marker for blood glucose control. Elevated readings indicate poor glycemic control, which is linked to a higher risk for adverse outcomes.

Women who require insulin therapy to treat gestational diabetes mellitus have higher blood pressure than whose diabetes was controlled by diet and exercise alone.

 

Polyhydramnios is an excess of amniotic fluid that could be a result of poor maternal blood glucose control, leading to an increase in infant urination. Polyhydramnios is associated with congenital abnormalities of the central nervous system & GI tract.

Close to half of the women with gestational diabetes will develop type 2 diabetes later in life.

 

Adverse Outcomes for the Baby Insulin promotes fat deposition. High maternal blood glucose causes three main problems: 1. higher fetal blood glucose levels 2. increased insulin production by the fetus 3. increased fetal weight gain

 

Congenital anomalies are increased if blood glucose was poorly controlled during the first 6-8 weeks of gestation. This may be indicative of undiagnosed diabetes prior to pregnancy. It may also be a result of polyhydramnios.

 

Macrosomia is a result of fetal exposure to high maternal plasma glucose concentrations and the infant’s pancreas producing large amounts of insulin. Insulin is a growth hormone, and increased secretions will lead to large adipose deposits in the infant’s organs, chest, & abdominal area. There is an increased risk for shoulder dystocia, which leads to an increased risk of injury to the infant’s head and neck. Macrosomia is seen in 20% of pregnancies complicated by gestational diabetes.

 

Hyperinsulinemia & hypoglycemia. At birth the oversupply of glucose from the placenta stops at delivery when the umbilical cord is cut; however,  the continued rapid production of insulin by the newborn pancreas leads to hypoglycemia. In many cases hypoglycemia has no symptoms, although sometimes the newborn is listless, limp, or jittery. To avoid hypoglycemia, early feedings with breast milk & frequent blood glucose monitoring are recommended (can drop <40 mg/dl in the first 12 hours). If the infant’s blood glucose remains low, the preferred treatment is IV glucose.

 

Respiratory distress syndrome, or RDS (specifically known as hyaline membrane disease) is a breathing disorder of premature newborns in which the air sacs (the alveoli) in a newborn's lungs do not remain open because the production of surfactant is absent or insufficient. Maternal diabetes puts an infant at risk for developing RDS. Premature infants are at risk for developing RDS.

 

And finally, exposure to high insulin levels in utero leads to increased glucose uptake into cells and the conversion of glucose to triglycerides (or fat). These changes can increase the fetal formation of fat and muscle tissue which can increase the likelihood of insulin resistance, type 2 diabetes mellitus, hypertension, and obesity later in life.

Other adverse outcomes of untreated gestational diabetes to the infant are hyperbilirubinemia which leads to jaundice, hypocalcemia, polycythemia, and poor feeding. The baby may also have low blood mineral levels. This problem can cause muscle twitching or cramping, but can be treated by giving the baby extra minerals.