By Martha A. Simpson, D.O., M.B.A.
Assistant Professor of Family Medicine
Ohio University College of Osteopathic Medicine

GESTATIONAL DIABETES -- COMMON, TREATABLE PREGNANCY COMPLICATION

Question: Our 29-year-old daughter, pregnant with our first grandchild, told us that her doctor thinks she might have gestational diabetes based on a blood sugar level of 145.  My daughter, before becoming pregnant, was quite thin and there’s no history of diabetes in either my family or my wife’s family.  Can you explain how gestational diabetes is diagnosed?  Also, is it likely to affect her child or my daughter’s future health?

Answer: Gestational diabetes is a type of diabetes that occurs only during pregnancy and disappears after delivery. It affects 2 to 5 percent of all pregnant women.

In general, diabetes is a disorder in which the body cannot properly handle glucose. This simple sugar molecule is produced when the foods that we eat are metabolized. The glucose is then transferred into the blood stream for distribution to the cells of the body where -- with the help of insulin -- it can be absorbed and converted to the energy. This is why some people refer to glucose as “blood sugar.”

In one kind of diabetes (Type I), the pancreas does not produce enough insulin for the cells to be able to absorb adequate amounts of glucose. In the more common variety of diabetes (Type II), on the other hand, the body produces enough insulin but the cells cannot utilize the insulin properly. A condition called insulin resistance. In gestational diabetes, specifically, the insulin is blocked by placental hormones.

This blocking of insulin by other hormones is called the “contra-insulin effect.” It usually begins around 20 to 24 weeks as the placenta enlarges and produces more hormones to support the pregnancy. Most pregnant women produce enough additional insulin to override the contra-insulin effect and keep their blood glucose levels in the normal range.

Pregnant women who are over 25, have a family history of diabetes mellitus, have high blood pressure, or are overweight, are at risk for developing gestational diabetes. Women with previous pregnancy complications such as a newborn weighing over 4000 grams, preeclampsia, previous stillbirth, or an infant with congenital anomalies are more likely to have gestational diabetes. The only one of these risk factors that your daughter appears to have is her age of 29.

The diagnosis of gestational diabetes is based on measurements of blood glucose. All pregnant women should be screened with a glucose challenge test (GCT). This sounds like what your daughter had. The woman drinks a 50 gram glucose drink (very sugary liquid) and the blood glucose is measured one hour later. If the blood sugar is below about 130 mg. (some sources say 140 mg.), the woman does not have gestational diabetes. If the GCT is positive, meaning an elevated sugar, then a 3-hour glucose tolerance test (GTT) is performed. This is necessary because not all women with a positive GCT have gestational diabetes.

Once a diagnosis of gestational diabetes is established, the patient will monitor her blood sugars at home, follow a specially prescribed diabetic diet for the duration of her pregnancy and may require referral to a diabetes specialist. The good news is that with proper diagnosis and management, the pregnancy should proceed normally. The bad news is that about half of the women who have gestational diabetes will develop Type II diabetes later in life.

"Family Medicine" is a weekly column. To submit questions, write to Martha A. Simpson, D.O., M.B.A., Ohio University College of Osteopathic Medicine, P.O. Box 110, Athens, Ohio 45701. Past columns are available online at http://www.FamilyMedicineNews.org.