What is Gestational diabetes (GD)?
Gestational diabetes develops only during pregnancy. It is a condition in which pregnant women with no previous history of diabetes exhibit high blood glucose levels. After developing intolerance to glucose and glucose intolerance continues beyond 24–28 weeks of gestation, then gestational diabetes takes place.
How is GD caused?
The precise mechanisms underlying gestational diabetes remain unknown. The hallmark of GD is increased insulin resistance. Gestational diabetes is caused when insulin receptors do not function properly. This is likely due to the presence of human placental hormones (Pregnancy hormones) that interferes with insulin receptors. Insulin enables the entry of the glucose into the cells and resistance of body to this insulin will prevent glucose entry from the bloodstream to the cells properly. As a result, glucose level is inappropriately elevated in the bloodstream.
How GD affects mother?
Gestational diabetes generally resolves once the baby is born. Based on different studies, the chances of developing GD in a second pregnancy incidental to first pregnancy are between 30 and 84%. A second pregnancy within 1 year of the previous pregnancy has a high rate of recurrence. GD also increases the risk of having an unnecessary caesarean episode.
How GD affects infants?
GD poses a risk to both mother and child. This risk is due to the uncontrolled high blood glucose levels and its consequences. The two main risks GD imposes on the baby are growth abnormalities and chemical imbalances after birth. Untreated GD can lead to seizures or stillbirth. The problem is not mitigated even if the delivery is successful. GD left untreated, will inappropriately increase the glucose (sugar) level in the body and when the foetus is exposed to consistently higher glucose levels, the level of insulin is elevated in foetus and growth-stimulating effects of insulin is accelerated, leading to excessive growth and a large body (macrosomia). After birth, these new-borns embark upon the high production of insulin and are at increased risk of low blood glucose levels. Macrosomia may affect 12% of normal women compared to 20% of women with GD. Untreated GD also interferes with maturation of babies vulnerable to respiratory distress syndrome due to incomplete lung maturation and impaired surfactant synthesis.
Classical risk factors for developing gestational diabetes are:
- GD gets common as the woman gets older. Mothers aged over 35 years of age are specifically susceptible
- A previous pregnancy which resulted in a child with macrosomia recognised by a condition in which the baby is abnormally large before birth (high birth weight: >90th centile or >4000 g (8 lbs 12.8 oz))
- GD is percolated down to the offspring belonging to a family revealing a history of type 2 diabetes (disease in which there is a high level of sugar in the blood)
- Genetic risk factor: There are at least 10 genes that are associated with an increased risk of gestational diabetes, most notably TCF7L2
- Being obese increases the risk of GD
- Smoking has also statistically shown positive relation with GD
What are the symptoms of GD?
Gestational diabetes is most commonly diagnosed by screening during pregnancy. Typically, women with GD may demonstrate increased thirst, increased urination, fatigue, nausea and vomiting, bladder infection, yeast infections and blurred vision.
Tests for GD
Screening glucose challenge test or O’Sullivan test
- First stage glucose tolerance testing – for the first time the test is performed between 24–28 weeks. You’ll drink a solution containing 50 grams of glucose. Your blood sugar level after an hour will be measured. A blood sugar level below 130 to 140 milligrams per deciliter (mg/dL) is usually considered normal. 80% of women with GD will be detected
- Second stage glucose tolerance testing – If your blood threshold is found higher than normal range, you’ll need a glucose tolerance test to determine if you have the condition. In this case, you are made to fast overnight and then blood sugar level would be measured the following morning. Then, you’ll drink another solution containing a relatively high concentration of glucose followed by a measurement of blood sugar level every hour for three hours. If at least, two of the blood sugar readings are higher than normal, you’ll be diagnosed with gestational diabetes. 90% of GD cases will be detected
Urinary glucose testing
Women with GD may have high glucose levels in their urine. Some 50% of women diagnosed with GD demonstrate glucose in their urine at some point during their pregnancy.
Treatment and Management
The main goal of treatment is to reduce the risks of GD for mother and the baby. Gestational diabetes is a treatable condition and women who have adequate control of glucose levels can effectively decrease these risks. Evidences show that if the glucose level is controlled, the foetal complications would be less. Generally, the treatments suggested are diabetic diet, exercise, and oral medication, however the food plan is often the first recommended target for strategic management of GD. Ifthe measures are inadequate to control glucose levels, insulin therapy may become necessary.
- Food plan – Weight gain is another factor that contributes to gestational diabetes. Eating the right kinds of food in healthy portion is very important. There is no ideal diet tailored for pregnant moms, therefore you should consult a registered dietitian or a diabetes educator to create a meal plan based on your current weight, pregnancy weight gain goals, blood sugar level, exercise habits, food preferences and budget. A strategic food plan coupled with a goal of ceasing the elevation of blood glucose level includes foods that are high in nutrition and fiber and low in fat and calories. They involve fruits, vegetables, whole grains. The diet should offer calories, typically 2,000 – 2,500 kcal with the exclusion of simple carbohydrates. Since insulin resistance is highest during mornings, breakfast carbohydrates need to taken in limited quantity.
- Exercise – Regular less stressful physical exercise is advised. Exercise lowers your blood sugar by stimulating your body to move glucose into your cells, where it’s used for energy. The choice of vigorous or light exercise depends on your current status.
- Insulin Therapy: Insulin is taken before meals to blunt surged level of glucose after meals. Insulin treatment also mitigates the problem of severe neonatal hypoglycaemia.
- Oral glycemic agents: Glyburide, a second generation sulfonylurea, has been shown to be an effective alternative to insulin therapy. Levemir injectable insulin can be an option for woman with GD.
- Treatment of polycystic ovarian syndrome with Metformin: Metformin on oral format is popular and preferred over the injections. Women having used it claimed that they are equally effective as insulin and decreases incidence of increased GD level. Metformin used in combination with insulin has been found more effective.
Women diagnosed with gestational diabetes in more than two previous pregnancies have an increased risk of developing diabetes mellitus in the future. Women requiring insulin to manage GD have a 50% risk of developing diabetes within the next five years. Children of women with GD have an increased risk for childhood and adult obesity due to the increased level of mother during pregnancy.
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