Gestational diabetes (GDM) can be defined as a kind of diabetes observed in pregnancy. It can be described as intolerance to glucose or elevated glucose level initiated or recognized in pregnancy, usually in the second or third trimester. Gestational diabetes affects almost 5-7% of all pregnancies in the US annually.
Gestational diabetes: pathophysiology, etiology, signs and symptoms, interventions, prognosis, and a nursing approach
Gestational diabetes (GDM) can be defined as intolerance to glucose or elevated glucose level initiated or recognized in pregnancy, usually in the second or third trimester. Gestational diabetes affects almost 5-7% of all pregnancies in the US annually. This implies that approximately 200000 women in the US have to deal with this condition every year. The risk factors associated with GDM are maternal age, history of GDM in previous pregnancy, family history, high birth weight babies, having polycystic ovarian syndrome and elevated body mass index prior to pregnancy. GDM is seen in population of women who also have a high likelihood of developing type 2 diabetes. They include Native American women, Hispanic/Latina women, African American and Asian women. For most women blood glucose levels go back to normal post delivery; however it has also been observed that many of the women with GDM are eventually diagnosed with type 2 diabetes (O’ Sullivan, 1970).
GDM is primarily a condition of a decreased sensitivity to insulin or increased resistance to insulin. It is now agreed that insulin resistance is a normal condition of pregnancy to ensure elevated glucose supply to the growing fetus. Insulin resistance is describes as the inability of insulin to produce an expected biological response of carbohydrate metabolism and clearance. The insensitivity to insulin is believed to be triggered by various pregnancy hormones, particularly the placental lactogen, somamatomammotropin, corticotrophin releasing hormone. These hormones interfere with the insulin and insulin receptor signaling pathway. Under normal physiological conditions, binding of insulin leads to phosphorylation and activation of insulin receptor. This activation then triggers a cascade of activation of various protein molecules leading to translocation of glucose transporter to the plasma membrane and influx of glucose. However, in pregnancy and later in GDM the insulin signaling pathway is compromised. This leads to decreased uptake of glucose in cells of skeletal muscle, hepatic tissue and adipose tissue and decrease suppression of glucose production in cells of hepatic tissue. To overcome the insulin resistance 1.5-2.5 times more insulin is secreted as compared to normal pregnancy. However, due to insulin resistance in GDM, the elevated insulin does not lead to proper glucose clearance. In women with untreated GDM, the fetus also gets glucose constantly by means of glucose transporter across the placenta. The fetus as a result produces more insulin and elevated insulin eventually leads to excessive birth weight (macrosomia). Babies with excess insulin become children who are at risk for metabolic syndrome, obesity and are at greater risk for getting type 2 diabetes as adults.
Gestational diabetes typically does not cause any noticeable signs or symptoms. Some of the common symptoms of diabetes such as severe thirst or increased urination are never observed. Other symptoms such as fatigue, swelling in feet can be associated as symptoms of pregnancy. As a result, proper and timely diagnosis is critical. A number of screening and diagnostic tests are routinely used to detect elevated glucose levels in pregnancy. Many obstetricians utilize a stepwise approach in which an elevated level on a screening test is followed by a more thorough diagnostic test. Alternatively, a more involved diagnostic test is the first choice for women who present risk factors (women with history of GDM or women who have polycystic ovarian syndrome). According to American college of Obstetrics all pregnant women should be screened for GDM based on their clinical history or laboratory testing. Clinical history of risk factors is able to capture only 50% of pregnancies. As a result, doctors usually employ 50 gm oral glucose challenge test as the screening method in the US. A cutoff point is set between 130-140 mg/100 mL for the blood glucose level one hour post ingestion. This leads to achievement of 80-99% sensitivity. Women who test positive for the glucose challenge test are given a 3 hour glucose challenge test. The GTT is performed in the morning following an overnight fast. A 75 or 100 g solution of glucose is ingested by the pregnant patient and blood is drawn to measure glucose at the beginning of the test and at set time interval(3 hours later). Most clinicians and doctors usually employ the more inclusive Carpenter/Coustan criteria. Using the Carpenter/Coustan criteria more women who are at risk of complications associated with GDM are diagnosed. The important thing to remember is that the intolerance for carbohydrate metabolism represented by elevated blood glucose either presented in 1 hour screening or in 3 hour GTT is associated with some adverse perinatal outcome and maternal complications.
The key to management of GDM is by regulating and maintaining glucose levels. This effectively leads to fewer serious fetal complications and improved quality of life for the mother. Providing counseling and education about eating healthy diet prior to pregnancy is suggested. Many of the women who are eventually diagnosed with GDM are able to manage the symptoms with changes to diet and exercise. A few women, however, need treatment to control their symptoms. Women with GDM on average need a daily caloric intake of 15 kcal · lb-1 · day-1 if they are normal weight. Use of low glycemic index (GI) diet in is recommended to all patients. A diet rich in fiber, fruits, vegetables and lean protein can lead to achievement of normal blood glucose levels. Counting of carbohydrates can also be a useful tool. The goal is to consume 30-45 g for breakfast, 45-60 g at lunch and dinner. 15-30 g of carbohydrate can be consumed as mid day snacks. Daily exercise of walking, swimming and low impact aerobic exercise 30 minutes a day can also help in lowering of blood glucose level. ACOG recommends that exercise heart rates should not exceed 140 bpm. Exercise increases the sensitivity to insulin and enhances insulin action. In addition to diet and exercise, an ultrasound is suggested at 36 weeks to measure the growth of the fetus and fetal weight. If there is likelihood of macrosomia some physicians recommend induction of labor (Carr & Gabbe, 1998).
Self-monitoring of blood glucose is vital for women with GDM (Landon & Gabbe, 2011). The goal of self-monitoring is to measure elevated blood glucose levels in the maternal blood. However, preventing hypoglycemia is just as important in women taking medication. The ACOG recommends measurement of fasting and 1 and 2 hours after eating. Fasting blood glucose should be < 95 mg/dl, 1-hour postprandial glucose < 140 mg/dl, and 2-hour postprandial glucose < 120 mg/dl (Metzger & Coustan, 1998). If diet and exercise still shows elevated blood glucose level, treatment with insulin might be required. Many women only require once a day (nightly) dose of neutral protamine insulin; while others need post meal fast-acting insulin to control elevated blood glucose levels. Since free insulin does not cross placenta there is no risk observed with the therapy for the fetus. In addition to insulin oral agents are also indicated for some GDM patients. Sulfonylureas, Metformin and Biguanides are generally safe for use in pregnancy. However, studies have demonstrated that treatment with insulin results in better maintenance and outcome of symptoms for mother and the baby (Rowan, Hague, Gao, Battin, Moore & Mig, 2009).
Most women with gestational diabetes who receive treatment go on to deliver healthy babies. The risk of complications increases only when blood glucose levels are not properly managed. All patients with GDM should be educated regarding lifestyle modifications that can be made to lower insulin resistance, including maintenance of normal body weight healthy diet and physical activity However when looking at long term effect of GDM, it is observed that between 30-85% women will eventually be diagnosed with type 2 diabetes. Women who get pregnant within a year of giving birth have greater risk of having type 2 diabetes. The risk is highest in women who required insulin, women who have had two previous pregnancies and obese women. Long term goal of follow up should be strategies toward prevention of diabetes, hypertension and cardiovascular disease that begin by accurate diagnosis of glucose abnormalities.
Nursing Approach: A study to evaluate the feasibility of a telemedicine system based on Internet and a short message service in pregnancy and its influence on delivery and neonatal outcomes of women with gestational diabetes mellitus (GDM) was carried out. 100 women diagnosed of GDM were randomized into two parallel groups, a control group based on traditional face-to-face outpatient clinic visits and an intervention group, which was provided with a Telemedicine system for the transmission of capillary glucose data and short text messages with weekly professional feedback. A diabetes nurse educator and an endocrinologist evaluated the patients' data online. The nurse educator then sent text messages making recommendations for nutritional changes or adjustments in insulin doses. The patients could text their questions or provide dietary information. Results. The study demonstrated that a telemedicine system could be useful as an alternative to traditional outpatient clinic visits. Although women in the telemedicine group attended the outpatient clinic less frequently than those in the control group, no deleterious effects on metabolic control, pregnancy, delivery, or on the newborn despite the presence of a higher proportion of insulin-using patients in the telemedicine group. (Perez-Ferre, Galindo, Fernandez, Velasco & Calle-Pascual, 2010)
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Metzger, B.E., & Coustan, D.M. (1998). Organizing Committee: Summary and recommendations of the Fourth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care 21 (Suppl. 2):B161 -B167.
O’ Sullivan, J. B. (1970). Gestational diabetes and its significance. Advances in Metabolic Disorder, 1:Suppl 1:339
Perez-Ferre, N, Galindo, M., Fernandez, M.D.,Velasco, V.Calle-Pascual, A.L.(2010) The outcomes of gestational diabetes mellitus after a telecare approach are not inferior to traditional outpatient clinic visits. International Journal of Endocrinology, 386941. doi: 10.1155/2010/386941. Epub 2010 Jun 10.
Rowan, J. A., Hague, W. M., Gao, W., Battin, M. R., Moore, M. P., Mig, I. (2008). Metformin versus Insulin for the Treatment of Gestational Diabetes. New England Journal of Medicine, 358 (19): 2003–2015