November 2007

Gestational Diabetes and the Importance of Postpartum Management
By Joyce Green Pastors, RD, MS, CDE
Today’s Dietitian
Vol. 9 No. 11 P. 14

CDR Learning Codes: 3020, 4130, 4180, 5190, 5310; Level 2

Most dietitians are familiar with gestational diabetes mellitus (GDM), but not all may know that GDM places women at risk for developing postpartum type 2 diabetes mellitus. With national attention focused on diabetes in all forms, the National Diabetes Education Program (NDEP) has launched a GDM Diabetes Prevention Initiative targeting both providers and women with a history of GDM.1 This article will explain why pregnant women with this syndrome are at risk, how to assess that risk, and what to do about it.

The American Diabetes Association (ADA) defines GDM as “glucose intolerance of variable severity.” Pregnant women can’t utilize the glucose in their blood effectively, resulting in hyperglycemia. In the second and third trimesters of pregnancy, the placenta produces large amounts of hormones that cause insulin resistance. Most pregnant women are able to double or triple their insulin production to compensate; those who are not able to increase insulin secretion develop GDM.2

On average, approximately 7% of pregnant women in the United States will be diagnosed with GDM, amounting to roughly 200,000 new cases each year.3,4 The prevalence rate ranges from 2% to 14% of all pregnancies depending on the population studied; the rate is two to four times higher in African Americans, Hispanics, American Indians, Asians, and Pacific Islanders compared with non-Hispanic white women.5

In addition to ethnicity, the risk of developing GDM is influenced by several factors, including excess body weight, inactivity, older age, history of GDM, previously giving birth to a large-for-gestational-age infant, and a family history of diabetes.3

Screening and Diagnosis
The onset of GDM is usually without symptoms, so maternal screening during pregnancy is essential for diagnosis and treatment. GDM is usually diagnosed between the 24th and 28th week of gestation, but high-risk individuals should be screened during the first trimester, preferably at the first prenatal visit. Women at low risk (younger than 25 years of age, normal weight, no history of abnormal glucose tolerance, low-risk ethnicity) do not need to undergo screening for GDM.3

In the United States, a two-step process is used for the screening and diagnosis of GDM. The first step is a 50-gram oral glucose challenge test. The blood glucose result from this test should be less than 140 milligrams per deciliter (mg/dl). If blood glucose is above 140 mg/dl, the second step is administration of a 100-g oral glucose tolerance test.

In the second test, blood glucose levels are measured at fasting and at one, two, and three hours postprandial. The diagnosis of GDM is made if two or more of the oral glucose tolerance test values are equal to or greater than the following:

• Fasting: 95 mg/dl;

• One hour postprandial: 180 mg/dl;

• Two hours postprandial: 155 mg/dl;
and
• Three hours postprandial: 140 mg/dl.3

Clinical Outcomes
High blood glucose levels must be evaluated and treated to prevent potential complications for the mother and child. In the mother, complications from GDM include preeclampsia, postpartum hemorrhage, progression of retinopathy, and nephropathy. In utero, the excess glucose can lead to macrosomia (more than 9 to 10 pounds at birth), as well as other complications such as jaundice, respiratory distress, stillbirth, neonatal death, and prematurity.

Blood glucose levels need to be monitored regularly at home—particularly fasting and postprandial glucose levels. These results can be recorded and shared with the healthcare provider and used to make necessary changes to lower blood glucose levels. Other parameters that need to be evaluated include weight changes, ketone levels, and food selection.

The most important clinical outcomes for GDM include the following:

• Achieving and maintaining normoglycemia (recommended glucose levels should be maintained at the following levels):

- Fasting plasma glucose at or below 105 mg/dl;

- One hour postprandial at or below 155 mg/dl; and

- Two hours postprandial at or below 130 mg/dl.

• Consumption of adequate energy to promote appropriate weight gain and avoid maternal ketosis. Weight gain recommendations for pregnancy are as follows:

- Underweight (body mass index [BMI] below 19.8) = 28 to 40 pounds;

- Normal weight (BMI 19.8 to 26) = 25 to 35 pounds;

- Overweight (BMI 26 to 29) = 15 to 25 pounds; and

- Obese (BMI above 29) = 15 pounds.

• Consumption of food providing nutrients necessary for maternal and fetal health. (Nutrition recommendations for GDM are included in Table 1.)

In some women, continued treatment may also involve initiation of insulin. The ADA recommends insulin therapy when blood glucose values exceed the fasting or postprandial glucose levels previously indicated for normoglycemia.3 Even though the elevated blood glucose levels usually return to normal after birth in most women, there is still an increased risk of continued glucose intolerance postpartum.

Risk Prediction for Type 2 Diabetes
Risk estimates for developing diabetes—usually type 2 diabetes—after GDM vary from 2% to 70%, depending on the population studied, criteria used for diagnosis, and length of follow-up.6 Studies that have focused on the immediate postpartum period (ie, the six-week postpartum follow-up glucose screening) have estimated the risk of glucose intolerance to be as high as 36% and diabetes to be 2% to 16%.7-9 The cumulative incidence of type 2 diabetes increases markedly in the first five years after delivery and appears to plateau after five years.

Recent studies have confirmed that the greatest predictors of early postpartum development of type 2 diabetes in women with GDM are the following:

• an elevated fasting plasma glucose during pregnancy (A fasting plasma glucose greater than 121 mg/dl during pregnancy increases the risk 21-fold of developing diabetes within four months postpartum.)10;

• use of insulin therapy during pregnancy11; and

• a BMI greater than 35 prior to or during pregnancy.12

Other reported predictors of risk for postpartum glucose intolerance in women with GDM include the following:

• degree of abnormality of the glucose tolerance test13,14;

• a genetic susceptibility (family history) of diabetes;

• a previous history of gestational diabetes;

• a gestational age greater than 35 years15;

• greater than recommended gestational weight gain16,17;

• postpartum weight retention16,17;

• weight gain between pregnancies16,17;

• physical inactivity18;

• race/ethnicity; and

• choosing not to breast-feed.

However, these risks are not independently associated with subsequent development of diabetes when glycemic variables (eg, glucose control during pregnancy) are included.6,19

It is important for healthcare providers to proactively foster awareness in women with GDM that their own and their child’s lifelong risk for developing type 2 diabetes is increased. In addition, regular follow-up, including testing for prediabetes and diabetes, should be promoted on an ongoing basis after a pregnancy complicated by GDM.

Postpartum Glucose Testing
Postpartum follow-up of at-risk women is currently inadequate. Both the ADA and the American College of Obstetricians and Gynecologists (ACOG) recommend postpartum glucose tolerance testing; however, their current screening recommendations conflict. The ADA recommends postpartum glucose screening at six weeks using a fasting glucose or an oral glucose tolerance test and follow-up with subsequent screening. The ACOG makes no specific recommendation regarding postpartum testing.

Two studies have examined the rate of postpartum glucose testing in women with a history of GDM. In the first retrospective study conducted on postpartum diabetes screening, only 37% of the 197 women at Massachusetts General Hospital and Baystate Medical Center completed a postpartum diabetes screening.20

The second retrospective study reported that in a cohort of 344 women at Women and Infants’ Hospital of Rhode Island, only 45% underwent postpartum glucose testing.21 Consistent recommendations, along with a professional and public health campaign to raise awareness of GDM as a risk predictor for diabetes, will be necessary to improve postpartum care of women diagnosed with GDM.12

The recommendations for follow-up of GDM from the recent Fifth International Workshop-Conference on Gestational Diabetes Mellitus are summarized in Table 2.

Postpartum Weight Management
The best predictor of postpartum weight retention is excessive weight gain during pregnancy.22 Thus, one approach to the problem of postpartum weight retention is to intervene during pregnancy and help women gain an appropriate amount of weight. Another factor believed to influence postpartum weight retention is breast-feeding. However, research indicates that breast-feeding status does not have a long-term effect on postpartum weight.23,24

The lack of attention to weight management in the postpartum period is a significant gap in our healthcare system.25 Even if there is a follow-up visit at the recommended six-week postpartum period, more than two thirds of women have not attained their prepregnancy body weight.26 During this critical six-week period, women have no access to health professionals who could help with weight management.

At the same time, because of the high risk associated with GDM and being overweight, there is a clearly defined opportunity to mount potentially effective preventive interventions with this postpartum population. Overweight women with a history of GDM should be counseled to reduce their risk factors for diabetes through lifestyle changes and medication, if necessary. While studies of the frequency of such counseling are scant, one survey of RDs who practiced in Cincinnati found that the provision of nutrition care in the postpartum period was “nonexistent.”25

Lifestyle Intervention
The Diabetes Prevention Program (DPP) was a multicenter clinical trial of men and women with impaired glucose tolerance randomized to receive either standard lifestyle intervention and placebo, metformin therapy, or an intensive lifestyle intervention.27 The goals of the intensive lifestyle intervention consisted of 7% or greater loss of body weight and maintenance of weight loss; dietary fat goal of less than 25% of calories from fat; calorie intake goal of 1,200 to 1,800 kilocalories per day; and 150 minutes or more of physical activity per week.

Even though women with a history of GDM enrolled in this trial lost less weight than the study population, they had a comparable reduction in the development of diabetes (55% compared with 58% overall reduction).

Previous findings have shown that predictors of weight gain over a three-year period included a high fat intake and physical inactivity.28 However, a review by Gunderson and Abrams noted that only a few studies have assessed the impact of behavioral factors such as physical activity and food intake on postpartum weight change.29 One such study conducted by Leermakers, Anglin, and Wing in 1998 reported the effect of a behavioral weight loss intervention, delivered via correspondence, in reducing postpartum weight.30 During the six-month treatment, subjects in the correspondence intervention lost significantly more weight than the control subjects (7.8 kilograms [kg] vs 4.9 kg) and lost a greater percentage of their excess postpartum weight (79% vs. 44%). A significantly greater percentage also returned to their prepregnancy weight (33% vs. 11.5%). Weight loss in the correspondence group was correlated with completion of self-monitoring records.

Keeping records and tracking progress with behavioral goals is another important step in making successful and long-lasting behavior changes. This should be included along with the important action steps of “making healthy food choices,” “being physically active,” and “breast-feeding your baby,” which are being promoted in the NDEP initiative to prevent type 2 diabetes in women with a history of GDM.

Record keeping can be accomplished by using a food and activity diary to write down for several days everything the patient eats and drinks and the number of minutes she is active. This information can be reviewed to assess changes that can be made and develop goals for making new behavior changes. Keeping track of progress can be helpful in achieving behavioral goals. It’s important to take small steps by making just one or two new changes each week. If your clients get off track, have them start again and keep going.

Preventing Type 2 Diabetes in Women With GDM
During pregnancy, women with GDM should be educated that glucose intolerance may not be temporary, that it can be modified with behavior changes, and that postpartum testing is important.31

In the NDEP’s GDM Diabetes Prevention Initiative, the following action steps have been recommended for prevention of type 2 diabetes in women who have been previously diagnosed with GDM:

• Get tested for diabetes six to 12 weeks after the baby is born, then every one to two years.

• Breast-feed, as it may lower the child’s risk for developing type 2 diabetes.

• Try to reach prepregnancy weight six to 12 months after the baby is born. Being overweight creates a higher risk for type 2 diabetes. If still overweight, work to lose at least 5% to 7% of body weight slowly over time and keep it off.

• Make healthy food choices such as fruits and vegetables, fish, lean meats, dry beans, whole grains, and low-fat or skim milk and cheese. Cut down on fatty, fried, and processed foods. Drink water or sugar-free sodas and fruit drinks. Eat smaller portions.

• Be active at least 30 minutes five days per week to help burn calories and lose weight.

• Talk to your doctor or healthcare provider if you plan to become pregnant again so he or she can provide consultation and assist you with planning.

Postpartum educational interventions offering continued support for healthy eating, regular physical activity, weight reduction, and breast-feeding are of high importance for all GDM mothers after delivery. Postpartum interventions for women with GDM who are at high risk for developing type 2 diabetes need to be developed and incorporated in settings such as Women, Infant and Children clinics and diabetes education programs throughout the country.

— Joyce Green Pastors, RD, MS, CDE, is a diabetes nutrition specialist at the University of Virginia Diabetes Center. She has published many articles and contributed to several books on nutritional management of diabetes.

Examination

1. Which of the following statements regarding diagnosing gestational diabetes (GDM) during pregnancy are true?
a. Women of high risk should be diagnosed during their first prenatal visit.
b. Women of low risk do not need to be screened for GDM.
c. All other women should be screened for GDM during weeks 24 to 28 of gestation.
d. All of the above

2. The three most important clinical outcomes for women diagnosed with GDM during pregnancy are:
a. achieving normoglycemia, adequate calories for appropriate weight gain, and adequate nutrition for maternal and fetal health.
b. adequate calories to prevent excess weight gain, adequate protein, and adequate complex carbohydrate intake.
c. preventing postpartum diabetes, normal hemoglobin A1c levels, and absence of ketosis.
d. achieving normoglycemia, minimizing weight gain, and adequate nutrient intake.

3. The most important risk factor(s) for predisposing a woman diagnosed with GDM to develop type 2 diabetes are:
a. a body mass index (BMI) greater than 35 and a previous pregnancy with a baby weighing more than 10 pounds at birth.
b. a BMI greater than 35, insulin therapy during pregnancy, and elevated glucose levels during pregnancy.
c. being older than 35 at time of first pregnancy, and having elevated glucose levels during pregnancy and an elevated hemoglobin A1c level.
d. receiving insulin therapy during pregnancy and having a previous pregnancy with a baby weighing more than 10 pounds at birth.

4. During pregnancy, women with GDM should be educated that glucose intolerance may not be temporary.
a. True
b. False

5. Studies indicate that the percentage of women with GDM who undergo postpartum glucose testing is:
a. 12% to 20%.
b. 22% to 35%.
c. 37% to 45%.
d. 55% to 64%.

6. Women with GDM should be screened for diabetes at which of the following times?
a. After delivery (one to three days)
b. Early postpartum (within six to 12 weeks)
c. One year postpartum
d. All of the above

7. The best predictor of postpartum weight retention, which is a risk factor for postpartum glucose intolerance, is which of the following?
a. BMI prior to pregnancy
b. Excessive weight gain during pregnancy
c. Elevated blood glucose levels
d. Lack of breast-feeding

8. Which of the following is an important action step for the prevention of type 2 diabetes in women diagnosed with GDM?
a. Lose the weight gained in pregnancy within 16 to 22 weeks postpartum
b. Eat more fruits and vegetables and eat less fat
c. Eat more calories to compensate for the needs of the baby
d. Drink adequate fluids

9. Lifestyle interventions focusing on postpartum women with GDM should include which of the following?
a. Healthier food choices
b. Lower fat intake
c. Increased physical activity
d. All of the above

10. Which of the following is the most important component of long-lasting behavioral change?
a. Giving clients structure and rules so they know exactly what to do
b. Providing group support on a weekly basis
c. Making big changes to achieve success quickly
d. Keeping records and tracking progress

References

1. National Diabetes Education Program. Accessed August 28, 2007.

2. Spellacy WN, Goetz FC. Plasma insulin in normal late pregnancy. N Engl J Med. 1963;268:988-991.

3. American Diabetes Association. Position statement: Gestational diabetes mellitus. Diabetes Care. 2003;27(Suppl 1): S103-S105.

4. Metzger BE, Coustan DR. Summary and recommendations of the fourth International Workshop-Conference on Gestational Diabetes Mellitus. Diabetes Care. 1998;21(Suppl2):B161-B167.

5. Beckles GLA, Thompson-Reid PE. Diabetes and Women’s Health Across the Life Stages: A Public Health Perspective. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Diabetes Translation; 2001.

6. Kim C, Newton KM, Knopp RH. Gestational diabetes and the incidence of type 2 diabetes: A systematic review. Diabetes Care. 2002;25(10):1862-1868.

7. Conway DL, Langer O. Effects of new criteria for type 2 diabetes on the rate of postpartum glucose intolerance in women with gestational diabetes. Am J Obstet Gynecol. 1999;181(3): 610-614.

8. Dacus JV, Meyer NL, Muram D, et al. Gestational diabetes: Postpartum glucose tolerance testing. Am J Obstet Gynecol. 1994;171(4): 927-931.

9. Damm P, Kuhl C, Bertelsen A, et al. Predictive factors for the development of diabetes in women with previous gestational diabetes mellitus. Am J Obstet Gynecol. 1992;167(3):607-616.

10. Schaefer-Graf UM, Buchanan TA, Xiang AH, et al. Clinical predictors for a high risk for the development of diabetes mellitus in the early puerperium in women with recent gestational diabetes mellitus. Am J Obstet Gynecol. 2002;186(4):751-756.

11. Catalano P, Vargo KM, Bernstein IM, et al. Incidence and risk factors associated with abnormal postpartum glucose tolerance in women with gestational diabetes. Am J Obstet Gynecol. 1991;165(4Pt1):914-919.

12. Ratner RE. Prevention of type 2 diabetes in women with previous gestational diabetes. Diabetes Care. 2007;30:S242-S245.

13. Cheung NW, Helmink D. Gestational diabetes: The significance of persistent fasting hyperglycemia for the subsequent development of diabetes mellitus. J Diabetes Complications. 2006;20(1):21-25.

14. Nohira T, Kim S, Nakai H, et al. Recurrence of gestational diabetes mellitus: Rates and risk factors from initial GDM and one abnormal GTT value. Diabetes Res Clin Pract. 2006;71(1): 75-81.

15. Lauenborg J, Hansen T, Jensen DM, et al. Increasing incidence of diabetes after gestational diabetes: A long-term follow-up in a Danish population. Diabetes Care. 2004;27(5):1194-1199.

16. Olson CM, Strawderman MS. Modifiable behavioral factors in a biopsychosocial model predict inadequate and excessive gestational weight gain. J Am Diet Assoc. 2003;103(1): 48-54.

17. Polley BA, Wing RR, Sims CJ. Randomized controlled trial to prevent excessive weight gain in pregnant women. Int J Obes Relat Metab Disord. 2002;26(11):1494-1502.

18. Zhang C, Solomon CG, Manson JE, et al. A prospective study of pregravid physical activity and sedentary behaviors in relation to the risk for gestational diabetes mellitus. Arch Intern Med. 2006;166(5): 543-548.

19. Lobner K, Knopff A, Baumgarten A, et al. Predictors of postpartum diabetes in women with gestational diabetes mellitus. Diabetes. 2006;55(3):792-797.

20. Smirnakis KV, Chasan-Taber M, Wolf G, et al. Postpartum diabetes screening in women with a history of gestational diabetes. Obstet Gynecol. 2005;106:1297-1303.

21. Russell MA, Phipps MG, Olson CL, et al. Rates of postpartum glucose testing after gestational diabetes mellitus. Obstet Gynecol. 2006;108(6):1456-1462.

22. Green GW, Smiciklas-Wright H, Scholl TO, et al. Postpartum weight change: how much of the weight gained in pregnancy will be lost after delivery? Obstet Gynecol. 1998;71:701-707.

23. Ohlin A, Rossner S. Maternal body weight development after pregnancy. Int J Obes. 1990;14(2):159-173.

24. Parker JD, Abrams B. Differences in postpartum weight retention between black and white mothers. Obstet Gynecol. 1993;81(5)768-774.

25. Krummel DA. Postpartum weight control: A vicious cycle. J Am Diet Assoc. 2007;107(1):37-40.

26. Walker LO, Sterlin BS, Timmerman GM. Retention of pregnancy-related weight in the early postpartum period: implications for women’s health services. J Obstet Gynecol Neonatal Nurs. 2005;34(4):418-427.

27. Diabetes Prevention Program Research Group: the Diabetes Prevention Program. Design and methods for a clinical trial in the prevention of Type 2 diabetes mellitus. Diabetes Care. 1999;22(4):623-634.

28. Sherwood NE, Jeffery RW, French SA, et al. Predictors of weight gain in the Pound of Prevention study. Int J Obesity Relat Metab Disord. 2000;24(4):395-403.

29. Gunderson EP, Abrams B, Selvin S. Does the pattern of postpartum weight change differ according to pregravid body size? Int J Obes Relat Metab Disord. 2001;25(6):853-862.

30. Leermakers EA, Anglin K, Wing RR. Reducing postpartum weight retention through a correspondence intervention. Int J Obes Relat Metab Disord. 1998;22(11):1103-1109.

31. Kitzmiller JL, Dang-Killduff L, Taslimi MM. Gestational diabetes after delivery. Diabetes Care. 2007;30:S225-S235.