Gestational Diabetes – Risks, Symptoms, and Treatment for Mother and Child

Gestational diabetes is one of the most common complications of pregnancy. The number of pregnant women affected has risen steadily in recent years across all age groups. This trend is linked, among other factors, to the rising average BMI (body mass index) of expectant mothers.

Furthermore, gestational diabetes occurs more frequently as the pregnant woman’s age increases. A screening test for gestational diabetes between the 24th and 28th weeks of pregnancy has therefore been part of prenatal care in Germany since 2012. An analysis of these screenings from 2014 and 2015 revealed an average prevalence of gestational diabetes in Germany of 13.2 percent. Among women who are 45 years of age or older, this metabolic disorder occurs in as many as 26 percent of all pregnancies.

The hormone insulin is released by the pancreas when blood glucose levels (blood sugar) are elevated and facilitates the uptake of glucose into the body’s cells. The hormones produced in greater quantities during pregnancy—particularly cortisol and progesterone—act as insulin antagonists, meaning they reduce insulin’s effectiveness. This condition is referred to as insulin resistance. A certain tendency toward insulin resistance develops in most pregnancies during the second trimester. This in itself is not yet considered a medical condition, but is thought to serve the purpose of prioritizing the supply of glucose to the fetus.

However, if insulin resistance can no longer be compensated for by increased insulin secretion, gestational diabetes develops. This can be the case, for example, if there were already subclinical, typically diet-related disturbances in glucose metabolism prior to pregnancy, insulin secretion was already elevated, and the pancreas was already operating near its capacity limit.

The major risk factors for gestational diabetes are being overweight, advanced maternal age, and the metabolic disorder polycystic ovary syndrome (PCOS). However, the limitation of insulin production capacity can also have genetic causes unrelated to these risk factors.

Gestational diabetes leads to impaired glucose tolerance, meaning elevated blood sugar levels after consuming carbohydrates. This usually does not cause any noticeable symptoms in those affected.

Increased thirst, rapid weight gain, and high blood pressure may be signs of this metabolic disorder. Furthermore, sugar in the urine and associated urinary tract and kidney infections occur more frequently. The fetus may exhibit growth abnormalities that are detectable via ultrasound.

Gestational diabetes is diagnosed using the oral glucose tolerance test (oGTT). For this test, 75 grams of glucose dissolved in 300 milliliters of water is consumed within five minutes in the morning on an empty stomach. Blood samples taken at various times (before glucose intake and one and two hours afterward) are then used to measure the temporal progression of the resulting rise in blood sugar.

Blood glucose levels above a certain threshold can thus confirm the presence of gestational diabetes. According to a recommendation by the International Association of the Diabetes and Pregnancy Study Groups (IADPSG), the current threshold values are 92, 180, and 153 mg/dl before glucose intake and one hour and two hours afterward, respectively. Incidentally, screening for gestational diabetes is one of the prenatal care services covered by health insurance.

If there are no risk factors, the short version of the oGTT is used. For this, you drink 50 grams of glucose dissolved in 200 milliliters of water at the doctor’s office, and a blood sample is taken one hour later. If the screening reveals an abnormal blood sugar level, a full glucose tolerance test, as described above, will be ordered.

Most women can normalize their blood sugar levels by changing their diet (largely replacing simple carbohydrates such as sugar and white flour with complex carbohydrates such as whole-grain flour, and eating smaller, more frequent meals) and increasing their physical activity. About one in ten women will also require insulin therapy. This involves injections using an insulin pen, often in combination with frequent blood sugar monitoring.

There is also ongoing discussion about using the oral diabetes medication metformin as either the sole treatment or as an adjunct. However, the safety and efficacy of this treatment have not yet been sufficiently proven. Metformin is therefore not approved for use by pregnant women in Germany and can only be prescribed in exceptional cases.

If gestational diabetes is detected early and blood sugar levels can be controlled through lifestyle changes or insulin therapy, the prognosis for both mother and child is good: Most affected women experience a completely normal pregnancy and delivery. Nevertheless, there remains a slightly elevated rate of complications. Gestational diabetes therefore increases the risk of:

• preeclampsia (a pregnancy-related condition characterized by high blood pressure)
• a birth weight significantly above average (so-called “sumo babies”) and the associated potential complications during vaginal delivery
• Preterm births
• Cesarean deliveries
• severe neonatal jaundice

After delivery, blood sugar metabolism largely returns to normal, and gestational diabetes usually resolves. However, there remains a significantly (up to seven times) increased risk of developing type 2 diabetes in the near future: After all, gestational diabetes should be understood as an indication of a pre-existing, underlying disturbance in blood sugar metabolism. For this reason, affected women should continue to have their blood sugar levels checked regularly even after delivery.