Gestational Diabetes

What is gestational diabetes, and why should you care? Well, let us discuss the first part of that question then we will go on to discover why it is important.

Gestational diabetes is defined by the American College of Obstetricians and Gynecologists as diabetes first diagnosed in pregnancy. It therefore may include women who have had diabetes before pregnancy, but were never diagnosed as well as those who only developed the disease as a result of pregnancy. And it is believed, though not proven, that the pregnant women who experience the most adverse effects of this disease are those who have had diabetes for a long time prior to pregnancy and therefore have already suffered some of itscomplications.

But what are risk factors for gestational diabetes? Some of them are similar to those for diabetes in general. You have an increased chance of developing gestational diabetes if you are a pregnant woman who is Hispanic, African American or Native American obese. You are also at increased risk for this condition if you have a personal history of gestational diabetes, have had a baby weighing 9 pounds or more, a history of unexplained stillbirth, family history of diabetes and/or chronic hypertension and either very young or older age.

Nevertheless, some women who develop this condition have none of the above characteristics.

Apart from pre-existing diabetes, what else causes gestational diabetes? Many possibilities exist. Several of the hormones (blood chemicals) that are produced in pregnancy have a tendency to make a woman resistant to insulin. These include progesterone, insulin-like growth factor and pregnenolone. While it is not important to remember these hormones by name, we always test women for glucose tolerance during pregnancy, because this condition places the woman and her fetus at greater risk for complications.

When should a pregnant woman be tested? There are two schools of thought on this one. Do you not love it when that happens? At any rate, the first school of thought recommends testing around 24-26 weeks gestational age. Another more conservative school of thought advocates testing all women who have the risk factors at their first prenatal care visit and around 24-46 weeks gestational age. The reasoning for this is that theoretically early diagnosis may allow for early treatment (presumably of persons with undiagnosed pre-existing diabetes) and fewer complications.

Detractors claim it is too costly to test everyone with risk factors. In the end, the individual physician will assess the patient's risk and decide with the woman whether she believes early testing is warranted.

The screening test for diabetes in pregnancy involves drinking a predetermined amount of a very sweet juice with a venous blood test done at 1 hour later to determine the glucose level. This is called a 1-hour glucose tolerance test, or 1-hr GTT. If the 1-hr GTT is elevated, a second round of testing is ordered, this time the woman is advised to fast prior to drinking a larger glucose load (100g) and blood testing is done at 0 minutes (fasting), and then at one, two and three hours after the drink.To be considered a positive test, indicating the woman has gestational diabetes, two or more of the hourly tests must be abnormal.

Some obstetricians pay closer attention to patients with one abnormal value, while others only focus on those who meet the strict criteria.

So why all the hullaballoo anyway? Well, it turns out that there are multiple risks associated with diabetes in pregnancy. Risks that apply both to the mother and to the fetus. For instance, mothers with gestational diabetes tend to have larger fetuses, may have greater tendency toward developing preeclampsia (a serious hypertensive disorder of pregnancy)and also have an increased risk of shoulder dystocia as well as being more likely to require delivery via cesarean section.

The fetuses of these women are larger due to longterm exposure to higher maternal blood sugar levels and they also tend to have increased risk of birth injury. The neonates exhibit poor ability to regulate their blood sugars initially and may have more respiratory problems in the first few days of life.

The National Institutes of Health publishes a free booklet about managing gestational diabetes.