Introduction
The application of walking exercise to special populations may serve as one of the best reasons yet to start on a walking program for improved health. This article will concentrate on one area that walking may have a profound impact on - that of Gestational Diabetes Mellitus during pregnancy. Regular exercise has effects in diabetes in general, and the focus here is its relevance with women who have two concerns - exercise during pregnancy, and dealing with the effects of diabetes during their gestation.
Diabetes in Pregnancy
Gestational diabetes is a disorder that affects a small but significant percentage of women during their pregnancies. It is defined as abnormally high blood sugar levels after a meal, and is associated with changes in hormonal levels during the second trimester on of pregnancy. These physical changes, as well as a family history, body weight above 115 % of ideal, and poor dietary patterns may predispose women to GDM.
Approximately 3-5% of women will encounter GDM during their pregnancy. It rate is higher in low socioeconomic status women, and in Hispanics. The results of uncontrolled GDM throughout pregnancy may result in fetal macrosomia (baby birth weight above nine pounds), and increases the risk for neonatal morbidity, compensatory low blood sugar reactions in the neo-nate, and cesarean section. It is the major cause of still births in the United States.
GDM is associated with fetal macrosomia because of high levels of insulin secretion by the fetus in response to high levels of maternal sugar that cross the placenta. The mother's own insulin is too large of a molecule to pass through the membrane, so the fetus must "overproduce" its own to compensate for the flood of sugar. Insulin is a growth hormone, and this is the cause of fetal macrosomia.
Screening for GDM
The usual diagnosis of GDM is by a 3 hour glucose tolerance test, whereby the mother drinks a 100 gram sugar solution, hoping to keep glucose levels from elevating too high over this time. The standard criteria is: Fasting levels < 105 mg/dl, 1 hour > 190, 2 hours > 165, 3 hours > 145 mg/dl. If a women is higher at any two time points, she is diagnosed with GDM.
Standard treatment of GDM is usually diet modification, staying with a meal plan higher in protein and fat to blunt the post-prandial (after meal) response. Women are encouraged to measure their own blood sugar levels at various times during the day with a home glucose monitor, which will record the results of a small drop of blood on a reflectance strip, and gives blood sugar results in a short time period.
If a standard diet is not successful in keeping blood sugar levels under control after meals, or during the fasting state, then insulin therapy is usually ordered by the doctor. It is done so because oral agents (used with many older adults with diabetes), is contraindicated in gestational diabetes, because of suspected risks to the fetus.
Insulin is administered around meal time on what is known as a "split routine"; or trying to match insulin amounts to types and amounts of foods eaten. If it is successful, then blood sugar levels will be in good control most of the time. Many women are not happy with the idea of taking insulin injections over the last two months of their pregnancy, and many are looking for other alternatives to this type of medical treatment.
Exercise and Diabetes
Exercise is one of the cornerstones of diabetic treatment. It has been used in type I (insulin-dependent), and type II (non insulin-dependent) diabetes for years. Exercise has an "insulin-like effect" on the muscle, causing blood sugar levels to drop, independently of insulin in most cases. It has been studied in many adults with diabetes, but until recently, not much in pregnant women.