Gestational Diabetes Mellitus: Incorporating the New Dietary Guidelines

Alicia Lindell, BS
Graduate Student/Dietetic Intern
Human Nutrition and Foods School of Medicine
West Virginia University
Morgantown, West Virginia

Liz Quintana, EdD, RD, LD, CDE
West Virginia University
Morgantown, West Virginia

Abstract

Gestational Diabetes Mellitus (GDM) is a serious complication of pregnancy. Obesity increases the risk for GDM, and the increasing rate of obesity in the nation has led to more cases of GDM. The condition not only affects the mother, but can cause poor outcome in the infant. The 2010 Dietary Guidelines for Americans provide recommendations for pregnant women and current research further expounds on recommendations and guidelines that should be implemented in managing women with GDM. A registered dietitian certified diabetes educator (RD and CDE) shares a case study of a first-time visit with a GDM patient.

Introduction

Gestational Diabetes Mellitus (GDM) is defined as glucose intolerance that is first recognized during pregnancy and develops in approximately 7% of all pregnancies (1,2). To identify more women with GDM and to reduce the health risks to the mother and fetus, the American Diabetes Association (ADbA) has adopted new guidelines for testing pregnant women for gestational diabetes. The International Association of Diabetes and Pregnancy Study Groups, which includes the ADbA, developed the new recommendations based on data from the Hyperglycemia and Adverse Pregnancy Outcomes (HAPO) study, which showed that the risk of maternal, fetal, and neonatal adverse effects increases directly with a mother’s glucose levels. The new criteria will increase the prevalence of GDM, because one abnormal value, not two, is sufficient to make the diagnosis. Table 1 outlines the new screening and diagnostic strategies (3).

Although many factors contribute to the onset of GDM, one of the major factors is obesity. Obese women are already predisposed to altered glucose and lipid metabolism, which puts them at a higher risk for developing GDM. The association between obesity and the risk for GDM is exponential: the greater the obesity, the higher the risk for GDM (3).

Whether associated with obesity or other causes, GDM affects not only the mother but also the health of her infant. The most common and significant neonatal complication associated with GDM is macrosomia: an oversized infant with a birthweight of more than 4000 g (>9 lb). Seen in 20% of pregnancies complicated by GDM, macrosomic infants have significantly greater fat mass (4,5). Fat accumulation in the infant is related to the blood glucose levels of the mother. As the mother’s blood glucose level increases, fetal fat accumulation also increases (6). Exposure to maternal diabetes also affects the infant later in life. Infants born to women with previous GDM are at increased risk for obesity and altered glucose metabolism (6). Exposure to maternal diabetes in utero puts these infants at an increased risk for obesity and also for cardiovascular disease and metabolic syndrome later in life (7). Women who have been diagnosed with GDM are now considered at risk for heart attack or stroke, according to the 2011 update of the American Heart Association’s cardiovascular disease prevention guidelines for women (8).

Although GDM is a complication of pregnancy and usually resolves immediately after delivery, up to one-third of women with GDM will test positive to impaired glucose metabolism or diabetes within 6 to 12 weeks after delivery. Another 15% to 50% of these women will develop type 2 diabetes (T2DM) within the next 10 years (9,10). In addition, women with previous GDM are 30% to 84% more likely to develop the condition with any subsequent pregnancy (11).

2010 Dietary Guidelines and Pregnancy

The 2010 Dietary Guidelines for Americans (DGA) are aimed at promoting health and preventing risks of chronic disease, such as T2DM (12). Because excessive weight gain and obesity increase the risk for GDM, and GDM increases the risk for T2DM, these new guidelines will have direct implications in GDM management.

The new DGA includes several recommendations concerning pregnant women. One recommendation is the avoidance of excessive weight gain, which is associated with suboptimal outcomes in the mother and infant. These outcomes include postpartum weight retention, increased risk of cesarean delivery, large-forgestational age infants, and obesity later in life. To prevent these undesirable health outcomes, the DGA Advisory Committee recommended that women achieve a healthy weight before conception. Pregnant women should engage in sound dietary practices and physical activity that will lead to gestational weight gains within the recommended guidelines and help to prevent postpartum weight retention. The new DGA also recommend breastfeeding because of its association with maternal postpartum weight loss (12).

Evidence-Based Guidelines for GDM
In addition to the DGA, current research provides more insight on the management of GDM. These guidelines include gestational weight gain, dietary interventions, and postpartum assessments. The Institute of Medicine has instituted guidelines for appropriate gestational weight gain (Table 2). Weight gain in excess of these guidelines is associated with poor outcomes. Excessive maternal weight gain increases the risk for neonatal hypoglycemia, macrosomia, low Apgar score, seizures, and polycythemia, and may also increase the infant’s risk for obesity later in life (13). Certain dietary interventions can help in the management of GDM. Women with GDM are encouraged to practice carbohydrate counting and/or use carbohydrate-controlled meal plans. The amount of carbohydrates consumed to allow for fetal growth and brain development should be at least 175 g (14). In addition to controlling for the amount of carbohydrates, the type and distribution also influence blood glucose levels. By decreasing processed carbohydrates and increasing fiber-rich foods, a woman can improve her glycemic control.

If a woman is obese, a 30% caloric restriction can also help improve glycemic control (14).

Women need continuous postpartum monitoring to detect signs of insulin resistance and possible onset of T2DM. Follow-up screening should be performed at 6 weeks after delivery, followed by annual screening of women with impaired fasting glucose or impaired glucose tolerance (14).

GDM Case Study: Stacy’s Story

What do registered dietitians discuss with their GDM patients? Sarah Edwards, RD, CDE, West Virginia University Hospitals Diabetes Education Center shares her visit with Stacy (name has been changed).

Stacy is 30 years old, white, 5’ 7” tall, weighs 257.5 lbs and was diagnosed with GDM at 26 weeks’ gestation. This is her fourth pregnancy. Although her obstetrical history included two miscarriages, this was her first time diagnosed with GDM. Her family history included both mother and maternal grandmother with T2DM. She is taking a prenatal multivitaminmineral supplement. She was given a glucose meter upon diagnosis by her physician’s staff.

Stacy tracked her blood glucose on her own before meeting with the RD. Although the ADbA does not recommend a daily monitoring schedule, research shows that in GDM, postprandial glucose concentrations are associated with a lower incidence of complications than preprandial concentrations (15). A frequent monitoring schedule enabled the health care providers and Stacy to assess the effectiveness of her meal and physical activity plan. Compared to the ADbA goals for glycemic control in GDM (Table 3), approximately 68% of Stacy’s results were within normal limits (WNL). Table 4 shows typical entries in Stacy’s blood glucose log after starting her meal and physical activity plan.

The determination of calorie needs is controversial. Energy recommendations must take into account sufficient calories without causing excessive weight gain or hyperglycemia. At this time, there is no formula supported by research to determine energy needs in overweight and obese pregnant women. Stacy led a sedentary lifestyle. Her desired weight was 135 lb. In estimating Stacy’s caloric needs, the following formula was used (13):

EER= 354- (6.91 x age) +
Physical Activity X
[9.36 x wt (desired) + 726 x Ht]
+340 for second trimester, or
+452 for third trimester

Stacy has gained 8 lb since becoming pregnant. Her weight gain goal for the pregnancy is 11 to 20 lbs (Table 2). The third trimester caloric needs were estimated at 2620 kcal. Based on her BMI, appetite, preferred food intake and physical activity, Stacy was encouraged to consume 2000 kcal/day (16). The foods sources of calories—fat, carbohydrates, and protein—were discussed in detail. During the RD visit, Stacy’s meal plan was established. The meal plan included 240 grams carbohydrates, or 16 choices (15 g carbohydrates per choice).

• Breakfast: 30-45 g
• Morning Snack: 30 g
• Lunch: 60 g
• Afternoon snack: 15-30 g
• Dinner: 60 g
• Bedtime: 30 g

Stacy’s post-breakfast glucose readings were above the target range, suggesting probable insulin resistance in the morning. She agreed to eat 30 to 45 g of carbohydrates for breakfast, and a mid-morning snack with 30 g carbohydrates. She was encouraged to have her fruit during the afternoon, rather than in the morning. Her fasting blood glucose remained WNL. The food log did not include fruit or milk products. Discussions with Stacy focused on how best to improve her nutrient intake, such as incorporating some fruit, yogurt, cottage cheese, and milk into her meal plan. She was encouraged to avoid added sugars, to use nonnutritive sweeteners in moderation, to eat salmon twice a week as a good source of omega-3 fatty acids, and to avoid fish that may contain higher amounts of mercury (e.g., shark, swordfish, king mackerel, and tilefish). The session concluded with a discussion on ways to avoid food borne illnesses, such as listerosis. Stacy’s weight was regularly monitored and her food intake was adjusted to keep her weight gain to about 0.5 lb/week. Her pregnancy and delivery progressed without complications. She delivered a 7 lb, 9 oz boy with blood glucose WNL. The sidebar on page 8 includes tips on successful management of GDM (17).

Conclusion

With the increasing obesity epidemic, more cases of GDM are appearing across the nation. Current research and the 2010 DGA provide registered dietitians and diabetes educators with the information necessary to counsel women. This advice includes how to manage blood glucose levels and to make lifestyle changes, such as increasing physical activity and monitoring gestational weight gain. How well blood glucose is managed during GDM will affect the woman’s own risk for T2DM, as well as her infant’s risk of developing diabetes.

References

1. Metzeger BE, Buchanan TA, Coustan DR, et al. Summary and recommendations of the fifth international workshop conference on gestational diabetes mellitus. Diabetes Care. 2007;30(suppl 2):S251–S260.
2. Rugge B, King V, Davis E, Schechtel M, Hickam D. Gestational Diabetes: Caring for Women During and After Pregnancy. U.S. Department of Health and Human Services; 2009. Agency for Healthcare Research and Quality Publication No. 09-EHC014-3. http://www.effectivehealthcare.ahrq.gov/ehc/products/107/163/2009_0804GDM_Clinician_final.pdf. Accessed November 29, 2010.
3. American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2011;34(suppl):S62–S69.
4. American Dietetic Association. Position of the American Dietetic Association and American Society for Nutrition: Obesity, reproduction, and pregnancy outcomes. J Am Diet Assoc. 2009;109:918–927.
5. Graves CR. Antepartum fetal surveillance and timing of delivery in the pregnancy complicated by diabetes mellitus. Clin Obstet Gynecol. 2007;50: 1007–1013.
6. Sacks DA. Etiology, detection, and management of fetal macrosomia in pregnancies complicated by diabetes mellitus. Clin Obstet Gynecol. 2007;50:980–989.
7. Metzger BE. Long-term outcomes in mothers diagnosed with gestational diabetes mellitus and their offspring. Clin Obstet Gynecol. 2007;50:972–979.
8. American Heart Association. Effectiveness-based guidelines for the prevention of cardiovascular disease in women-2011Update: Table 2. Classification of CVD risk in women.http://www.newsroom.heart.org/index.php?s=43&item=1239 Accessed February 17, 2011.
9. England LJ, Dietz PM, Njoroge T, et al. Preventing type 2 diabetes: public health implications for women with a history of gestational diabetes mellitus. Am J Obstet Gynecol. 2009;200: 365.e1–365.e8.
10. National Center for Chronic Disease Prevention and health Promotion. National Diabetes Fact Sheet, 2011. http://www.cdc.gov/diabetes/pubs/pdf/ndfs_2011.pdf Accessed February 18, 2011.
11. Nelson AL, Le MHH, Musherraf Z, VanBerckelaer A. Intermediate term glucose tolerance in women with a history of gestational diabetes: natural history and potential associations with breastfeeding and contraception. Am J Obstet Gynecol. 2008;198: 699.e1-699.e8.
12. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Report of the Dietary Guidelines Advisory Committee on the Dietary Guidelines for Americans, 2010.http://www.cnpp.usda.gov/DGAs2010-DGACReport.htm. Accessed December 20, 2010.
13. Institute of Medicine. Weight Gain during Pregnancy: Reexamining the Guidelines. Washington, DC: National Academies Press; 2009.
14. American Dietetic Association. Position of the American Dietetic Association: nutrition and lifestyle for a healthy pregnancy outcome. J Am Diet Assoc. 2008;108:553–561.
15. American Diabetes Association. Standards of medical care in diabetes—2011. Diabetes Care. 2011;34(suppl):S11–S61.
16. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, DC: National Academies Press; 2002.
17. Thomas A, Gutierrez YM. American Dietetic Association Guide to Gestational Diabetes Mellitus. Chicago, IL: American Dietetic Association; 2005.

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