Gestational Diabetes Case File

Gestational Diabetes Case File

Eugene C. Toy, MD, Edward Yeomans, MD, Linda Fonseca, MD, Joseph M. Ernest, MD

Case 20

A 28-year-old G2P1001 at 26 5/7 weeks presents to your office following completion of her 1-hour glucose screening. The 1-hour glucose measurement result was 165 mg/dL. This pregnancy has been unremarkable thus far and she has no significant obstetric or medical history. She is of Hispanic descent and her BMI is 35 kg/m2. She screened negative for gestational diabetes mellitus (GDM) during her prior pregnancy, however, that pregnancy was significant for the delivery of a term female infant weighing 10 and 3 oz (4.7 kg)

➤ What is the next step in management of this patient?

➤ What risk factors does this patient have for gestational diabetes mellitus?

➤ What are treatment options for women with gestational diabetes mellitus?

➤ What are potential fetal implications for babies born to mothers with gestational diabetes?

➤ What are potential maternal implications following a pregnancy complicated by gestational diabetes?

ANSWERS TO CASE 20:

Gestational Diabetes

Summary: A multiparous woman presents with an abnormal glucose screening test result.

➤ Next step in management of this patient: She should complete a 3-hour oral glucose tolerance test.

➤ Risk factors this patient have for gestational diabetes mellitus: This patient possesses multiple risk factors for developing gestational diabetes including age greater than 25 years, belonging to an ethnic group with an increased risk for the development of type 2 diabetes, obesity, and prior macrosomic infant.

➤ Treatment options for women with gestational diabetes mellitus: While insulin therapy is the gold standard for diabetes therapy, the use of glyburide, an oral hypoglycemic agent, has been found to be effective in select patients.

➤ Potential fetal implications for babies born to mothers with gestational diabetes: Infants born to mothers with gestational diabetes are at risk of fetal overgrowth. Recent studies suggest that there is increased risk of longterm chronic health problems in these infants such as early onset diabetes, hyperlipidemia, and obesity.

➤ Potential maternal long-term implications following a pregnancy complicated by gestational diabetes: Women who develop gestational diabetes mellitus are at increased risk of developing type 2 diabetes during the years following their pregnancy. These risks may be reduced with interventions such as maternal weight loss through diet and exercise.

ANALYSIS

Objectives

1. List the risk factors for gestational diabetes.
2. Describe the complications of gestational diabetes.
3. Describe the diagnosis and management of GDM.

Considerations

Gestational diabetes mellitus (GDM) is defined as carbohydrate intolerance first recognized during pregnancy. This represents both new-onset glucose intolerance as well as previously undiagnosed pregestational diabetes mellitus. Gestational diabetes complicates approximately 2% to 6% of all gestations in the United States although certain racial and ethnic groups do experience rates which are significantly higher. Ethnic groups that are considered to be at high risk for the development of GDM include persons of Hispanic heritage, persons of African descent, native Americans, southeast Asians, Pacific Islanders, and indigenous Australians1,2 (Level III).

This patient has an increased risk for developing GDM due to her ethnic background, obese status, age greater than 25 years, and history of giving birth to a macrosomic infant. If GDM is confirmed she would need to be counseled that there is an increased risk of maternal and neonatal morbidity which is

related to the degree of insulin resistance. Neonatal morbidity includes increased rates of macrosomia defined as greater than 90% for gestational age, increased risk of birth trauma, and increased neonatal admissions due to metabolic derangements such as hypoglycemia, hyperbilirubinemia, and hypocalcemia1 (Level III). We also know that infants born to mothers with GDM experience increased rates of childhood obesity and chronic health complications including early-onset type 2 diabetes mellitus, hyperlipidemia, and obesity3 (Level II-2).

Maternal morbidity includes increased cesarean delivery rates, increased rates of pregnancy associated hypertensive disorders, and an increased risk of developing type 2 diabetes mellitus in the years following the pregnancy. The risk of developing type 2 diabetes is as high as 70% in the years following a gestation complicated by GDM1 (Level III).

The next step in the management of this patient is a 3-hour oral glucose tolerance test (OGTT). She should be instructed to return to the office while fasting following a period of at least 3 days of an unrestricted carbohydrate diet. After obtaining a fasting glucose measurement, a standard 100 g glucose load is given followed by plasma glucose measurements taken hourly for 3 hours. If two or more glucose measurements are abnormal, she meets the criteria for GDM. Insulin therapy or oral glyburide are treatment options for glycemic control during pregnancy if diet control is unsuccessful.

APPROACH TO

Gestational Diabetes

Screening for GDM

There has been much debate regarding the utility of screening and the best modality which should be used to screen individuals. Selective screening based on risk factors would reduce number of women requiring screening by 10% to 15%, however, it would fail to identify one-third to one-half of affected individuals4,5 (Level II-2). For this reason the American College of Obstetricians and Gynecologists (ACOG) supports universal screening in all persons except those deemed to be at low risk. This includes women less than 25 years of age, women belonging to an ethnic group with a low prevalence of diabetes, women with body mass index less than 25, and women with no first-degree relative with diabetes2 (Level III).

In our practice we screen all patients by risk factors during the first prenatal visit. Patient’s deemed to be at high risk for developing GDM undergo early screening. Women who screen positive are triaged appropriately and those who screen negative are rescreened at 24 to 28 weeks with the general population of patients. Risk factors which trigger early diagnostic testing includes but is not limited to maternal obesity defined as maternal weight greater than 120% ideal body weight, first-degree relatives with diabetes, maternal polycystic ovarian syndrome, or a prior pregnancy complicated by gestational diabetes, fetal macrosomia, or unexplained fetal or neonatal demise6 (Level III).

A two-step approach has been recommended in order to identify women with GDM. The first step involves a 50 g 1-hour screening test, and the second step utilizes a 100 g 3-hour diagnostic test for those women identified via the initial screening test.

The 1-hour OGTT can be completed at any time of day without the need for an overnight fast. Women are given a 50 g glucose load and plasma glucose levels are measured 1 hour after completion of the load. It is appropriate to use either 140 mg/dL or 130 mg/dL as a positive result for the 1-hour screening test. Use of the 140 mg/dL value identifies 14% to 18% of women who will require the diagnostic testing with 80% sensitivity. Use of the 130 mg/dL value identifies 20% to 25% of women who will require the diagnostic testing with 90% sensitivity6,7 (Level III).

Diagnosis

The gold standard for the diagnosis of GDM is the 100 g, 3-hour OGTT. The 3-hour OGTT is reserved for women with positive screening results. This test should be completed following an overnight fast. Patients are instructed to adhere to an unrestricted diet prior to the administration of the test with at least 150 g of carbohydrates per day for at least 3 days prior to the test. The purpose of carbohydrate loading is to avoid carbohydrate depletion which could increase the risk of false-positive results. Fasting plasma glucose levels are measured prior to the consumption of a standardized 100 g glucose load. Following completion of the load blood plasma glucose levels should be measured at 1, 2, and 3-hour intervals. A positive result is characterized by at least two abnormal values. There are two sets of values which are used to interpret 3-hour OGTT result: Carpenter and Coustan criteria and the National Diabetes Data Group (NDDG). Values described by Carpenter and Coustan for fasting, 1-, 2-, and 3-hour measurements are as follows, 95, 180, 155, and 140 mg/dL. Corresponding NDDG values are 105, 190, 165, and 145 mg/dL. Use of the Carpenter and Coustan criteria is associated with an additional 50% detection rate of women at risk of similar morbidity as are women in the less stringent NDDG identified population. For this reason, the Fourth International Workshop Conference on GDM advocated the use of Carpenter and Coustan, although both set of criteria are acceptable8 (Level III).

The World Health Organization supports the use of a 2-hour 75 g diagnostic test utilizing values concurrent with fasting, 1- and 2-hour values set for the 3-hour OGTT. A positive result requires at least two abnormal values. The American Diabetes Association recognizes this as an acceptable option although at this time the 100 g test is generally used in the United States8 (Level III).

Recently completed, the hyperglycemia and adverse pregnancy outcome (HAPO) trial looked at maternal and fetal implications of maternal hyperglycemia less than that which is diagnostic for diabetes. The HAPO trial utilized a one-step diagnostic process with a 75 g 2-hour test. They found a linear relationship between maternal glucose levels and adverse outcomes, even at glucose concentrations below those that are usually diagnostic of GDM. The results of this study are likely to alter not only classification criteria for GDM but are also likely to modify treatment modalities9 (Level I).

Therapeutic Interventions

Medical nutrition therapy is the first line of therapy in the treatment of women with GDM. The ultimate goal for medical nutrition therapy is to achieve euglycemia without inducing ketosis2,10,11 (Level I, III). Once the diagnosis of GDM has been made, the woman should receive counseling from a registered dietician or other knowledgeable persons. Recommended diets should aim to decrease total fat intake and to incorporate complex carbohydrates and foods with high fiber content. Good carbohydrates should comprise approximately 35% to 40% of daily caloric intake with protein and fats equally accounting for the rest of the daily diet. Women with BMI within normal limits should have a target goal of 30 kcal/kg/d. This goal should be reduced to 25 kcal/kg/d for obese patients and 20 kcal/kg/d for morbidly obese patients. Patients should be counseled to maintain active lifestyle as exercise has been found to improve insulin sensitivity2,12 (Level III).

Women being treated with medical nutrition therapy should be followed closely with the goal of maintaining fasting glucose levels less than 105 mg/dL and 1-hour glucose levels less than 140 mg/dL. McFarland et al published an observational study in order to determine the length of time needed to

achieve good glucose control. They found that fasting glucose levels strongly correlated with success of medical nutrition therapy. They found that women with fasting levels greater than 95 mg/dL did not significantly improve glycemic control after 1 week, while women with fasting levels less than 95 mg/dL continued to show improvement after 2 weeks13 (Level II-2). For this reason most clinicians advocate 2 weeks for attempting dietary therapy prior to initiating alternative therapies.

Carbohydrate metabolism is very different during pregnancy due to the influence of pregnancy associated hormones such as growth hormones, corticotrophin- releasing hormone, human placental lactogen, and progesterone. During pregnancy women experience postprandial hyperglycemia and fasting hypoglycemia in order to provide adequate glucose for the fetus14 (Level III). These factors make some insulin formulations more appropriate for use in pregnancy. Antibody-free human insulin is the gold standard for glycemic control during pregnancy, however, a number of insulin analogs have shown promise in the treatment of women with GDM10 (Level III). In our practice we generally use intermediate acting NPH for basal glucose management and insulin lispro, an ultrafast-acting formulation, for postprandial coverage.

Insulin has been traditionally the standard for treatment in those who have failed medical nutrition therapy because it achieves glucose control without the risk of insulin transfer across the placenta. However, emerging evidence in recent years has resulted in a growing acceptance of the use of oral agents in the treatment of GDM. The use of oral hypoglycemic medications offers less invasive alternatives to some women with GDM, allowing them to avoid insulin injections. Perhaps the most well-studied agent available currently is glyburide, a second-generation sulfonylurea. Glyburide is an insulin secretagogue which acts by stimulating insulin secretion after meals. There appears to be little or no placental transfer decreasing concerns of possible fetal effects. Glyburide has been shown in randomized controlled trials to be comparable to insulin in terms of efficacy with similar obstetric and neonatal outcomes with significantly fewer episodes of hypoglycemia15,16 (Level I, III). In Langer’s trial, the “glyburide failure rate” was approximately 18%15 (Level I). The peak effect is single dosing preferably 1 hour before meals is recommended with a maximum of 20 mg per day.

The use of metformin has primarily been evaluated in patients with polycystic ovarian syndrome and type 2 diabetes as means of improving insulin resistance. Ovulation induction and possible reductions in first-trimester losses have been reported with the use of metformin. Although the efficacy of metformin appears comparable to insulin therapy11 (Level I), the level of placental transfer brings into question possible fetal implications. Further studies documenting the safety of metformin for the treatment of gestational diabetes are needed before its use can be supported11,17 (Level I, III).

Fetal Surveillance and Delivery

Women requiring pharmacologic therapy for GDM and those with additional comorbid conditions who do not require medical therapy should undergo increased surveillance to improve neonatal outcome. Early ultrasound evaluations are useful to provide accurate dating, and anatomy surveys performed between 18 and 20 weeks’ gestation are important to evaluate for congenital anomalies. Gestational diabetes mellitus is not associated with the structural anomalies seen in gestations complicated by pregestational diabetes, although it is reasonable to consider these complications for those women diagnosed early in pregnancy who may represent undiagnosed type 2 diabetes. Ultrasound evaluations should be performed during the third trimester to assess for signs of fetal hyperglycemia including fetal overgrowth and polyhydramnios2,8 (Level III). A number of studies have looked into the utility of third-trimester ultrasound measurements to assist in decisions regarding therapy. Kjos et al found that in women with GDM and fasting hyperglycemia, use of ultrasound measurements in addition to glucose measurements were able to identify women who did not require insulin therapy without increasing morbidity18 (Level I).

Antenatal testing should begin no later than 32 weeks’ gestation in women requiring insulin or oral hypoglycemic therapy. Women treated with diet therapy alone may wait for testing to begin at 38 weeks. Antenatal surveillance should be carried out at least weekly with fetal non-stress tests or biophysical profile evaluations19 (Level III). Decisions regarding timing of delivery should be based on level of control and maternal and neonatal morbidity. However, generally delivery should occur between 39 and 40 weeks in women with good control pharmacologic therapy. If delivery prior to 39 weeks is undertaken due to suboptimal glycemic control, documentation of fetal lung maturity via amniocentesis should be considered20 (Level II-2). Route of delivery should be based on the estimated fetal weight (EFW) by ultrasound and most would agree that elective cesarean delivery should be discussed and offered to diabetics with EFW of greater than 4500 g due to the potential for shoulder dystocia.

Postpartum Management

All women diagnosed with GDM should be screened for overt diabetes mellitus during the postpartum period. The Fifth International Workshop- Conference on Gestational Diabetes Mellitus advocates the use of a 75 g oral glucose tolerance test at least 6 weeks postpartum21 (Level III). Fasting glucose levels greater than 126 mg/dL or 2 hour values greater than 200 mg/dL are diagnostic for diabetes mellitus2 (Level III). Patients meeting these criteria should be referred to an internist for continued care.

Contraception options are very important to consider in this population as we know that recurrent pregnancies in a woman with GDM increase her risk for overt diabetes mellitus22 (Level III). Contraception options with low-dose combinations of estrogen and progesterone do not appear to increase the risk of developing type 2 diabetes. This includes oral contraceptive pills, vaginal ring inserts, and transdermal delivery systems. In contrast, progestinonly pills and depot progesterone preparations have been associated with impairment of carbohydrate metabolism and increased progression to type 2 diabetes in some populations. For this reason they should be reserved for patients who are not candidates for alternative methods. For women considering more long-term contraception, intrauterine devices are a good option. Both copper IUD devices and levonorgestrel IUD devices may be used with good safety profiles18,23,24 (Level I, II-2, III).

Breast-feeding should be encouraged for both infant and maternal benefits. The data are inconclusive regarding the association between breast-feeding and type 2 diabetes25 (Level III). There is, however, data which show that women who breast-feed for extended periods of time experience a greater decrease in weight, which may decrease their risk of developing type 2 diabetes26 (Level III). In terms of neonatal effects, breast-feeding has been associated with decreased risk of childhood obesity and the development of diabetes mellitus compared to formula-fed infants27,28 (Level II-2).

Comprehension Questions

20.1 A 32-year-old G3P2002 Caucasian female presents for prenatal care at 9 weeks’ gestation. Her obstetrical history is significant for GDM with her last pregnancy only ending in a term delivery of a 7 lb (3 kg) infant. She was not screened postpartum and denies any medical complications. Her BMI is 29 kg/m2. When would you consider screening for GDM?

A. 9 weeks

B. 16 weeks

C. 28 weeks

D. 6 weeks postpartum

20.2 A 35-year-old woman at 29 weeks’ gestation is diagnosed with gestational diabetes. She is placed on a 2200 cal ADA diet. Her blood sugars over the next 2 weeks are as follows: 

Fasting: 110 mg/dL; 105 mg/dL; 107 mg/dL; 113 mg/dL; 109 mg/dL

2 hour after breakfast: 124 mg/dL; 136 mg/dL; 122 mg/dL; 140 mg/dL

2 hours after lunch: 139 mg/dL; 144 mg/dL; 123 mg/dL; 111 mg/dL

2 hours after dinner: 130 mg/dL; 143 mg/dL; 132 mg/dL; 125 mg/dL

Which of the following is the best management of this patient at this time?

A. Initiation of insulin subcutaneously.

B. Continue diet and monitor blood sugars for 1 week more.

C. Admission to the hospital for intravenous insulin therapy.

D. Fetal ultrasound, and if EFW is 2000 g or greater then delivery.

ANSWERS

20.1 A. This patient should be screened for GDM without delay. A history of GDM increases the risk of this patient having GDM this pregnancy as well as type 2 diabetes mellitus. A 3-hour 100 mg OGTT

should be ordered. If she meets criteria for GDM, she is likely to have pregestational diabetes given her early gestational age and should be counseled and managed accordingly. If she does not meet criteria for GDM then repeat testing should be performed at 24 to 28 weeks.

20.2 A.With the fasting glucose levels higher than target of 90 to 100 mg/dL and 2-hour postprandial levels exceeding targets of 120 mg/dL, despite 2 weeks of diet, then pharmacologic therapy should be started. Insulin is appropriate, although an oral hypoglycemic agent is also acceptable.

Clinical Pearls

See US Preventive Services Task Force Study Quality levels of evidence in Case 1

➤ Risks factors for GDM include maternal obesity defined as maternal weight greater than 120% ideal body weight, first-degree relatives with diabetes, maternal polycystic ovarian syndrome, or a prior pregnancy complicated by gestational diabetes, fetal macrosomia, or unexplained fetal or neonatal demise. In addition certain ethnic groups experience higher rates of GDM: persons of Hispanic heritage,persons of African descent, native Americans, southeast Asians, Pacific Islanders, and indigenous Australian persons (Level III).

➤ All women with GDM should be screened for overt diabetes during the postpartum period. Glyburide crosses the placenta and is considered a safe alternative to insulin for treatment of GDM (Level III).

➤ Antenatal testing should be initiated by 32 weeks for patients with GDM not managed by diet alone. Patients managed with diet should begin antenatal testing at 38 weeks (Level III).

➤ It is important to counsel women with GDM regarding contraception choices.Although low-dose combination options are preferred over progestin- only options, they are preferred over no therapy at all. Following a pregnancy complicated by GDM, each subsequent gestation increases her risk of developing type 2 diabetes mellitus (Level II-3).

CONTROVERSIES

• Carpenter and Coustan diagnostic criteria for the 3-hour 100 g OGTT is recommended by the Fourth and Fifth International Workshop-Conference of GDM and endorsed by ACOG; however, these expert bodies recognize that other alternative tests are acceptable.
• Further data in pregnancy are needed before the use of metformin for the treatment of GDM can be recommended.

REFERENCES

1. Hollander, MH, Paarlberg KM, Huisjes AJ. Gestational diabetes: a review of the current literature and guidelines. Obstet Gynecol Surv. 2007;62(2):125-136 (Level III). 

2. ACOG Practice Bulletin. Clinical management guidelines for obstetriciangynecologists. Number 30, September 2001. Obstet Gynecol. 2001;98(3):525-538 (Level III). 

3. Catalano PM, Farrel K, Thomas A, et al. Perinatal risk factors for childhood obesity and metabolic dysregulation. Am J Clin Nutr. 2009;90(5):1301-1313 (level II-2). 

4. Minsart AF, Lescrainier JP, Vokaer A. Selective versus universal screening for gestational diabetes mellitus: an evaluation of Naylor’s model. Gynecol Obstet Invest. 2009;68(3):154-159 (Level II-2). This study compared the ability of selective versus universal screening to effectively identify women with GDM. It was found that selective screening allowed 15% of women to avoid laboratory testing, however, 50% of women who would have screened positive were missed. 

5. Coustan DR, Nelson C, Carpenter MW, et al. Maternal age and screening for gestational diabetes: a population-based study. Obstet Gynecol. 1989;73(4):557-561 (Level II-2). 

6. Hanna FW, Peters JR. Screening for gestational diabetes; past, present and future. Diabet Med. 2002;19(5):351-358 (Level III). 

7. Ben-Haroush A, Yogev Y, Hod M. Epidemiology of gestational diabetes mellitus and its association with Type 2 diabetes. Diabet Med. 2004;21(2):103-113 (Level III). 

8. Metzger BE, Phelps PR, Dooley SL. The mother in pregnancies complicated by diabetes mellitus. In: Porte D, Robert S, Baron A, eds. Ellenberg and Rifkin’s Diabetes Mellitus. 6th ed. New York, NY: The McGraw-Hill Companies Inc.; 2003 (Level III). 

9. Metzger BE, Lowe LP, Dyer AR et al. Hyperglycemia and adverse pregnancy outcomes. N Engl J Med. 2008;358(19):1991-2002 (Level I). Pregnant women with hyperglycemia not diagnostic for diabetes were evaluated to explore the association between hyperglycemia and adverse pregnancy outcome. This study included 25,505 pregnant women from 15 different centers in 9 countries. The investigators found that there was a strong continuous association between mild maternal hyperglycemia and obstetric morbidity including an increase in cesarean delivery, neonatal macrosomia, and neonatal hypoglycemia. 

10. Langer O, Hod M. Management of gestational diabetes mellitus. Obstet Gynecol Clin North Am. 1996;23(1): 137-159 (Level III). 

11. Moore LE, Briery CM, Clokey D et al. Metformin and insulin in the management of gestational diabetes mellitus: preliminary results of a comparison. J Reprod Med. 2007;52(11):1011-1015 (Level I). 

12. Langer O. Management of gestational diabetes: pharmacologic treatment options and glycemic control. Endocrinol Metab Clin North Am. 2006;35(1):53-78, vi (Level III). 

13. McFarland MB, Langer O, Conway DL, Berkus MD. Dietary therapy for gestational diabetes: how long is enough? Obstet Gynecol. 1999;93(6):978-982 (Level II-2). This study evaluated the length of time needed for dietary therapy to achieve good glycemic control. Investigators treated women with GDM for 4 weeks while monitoring blood glucose levels. The investigators found that fasting blood glucose levels were most predictive in terms of success with diet alone and that women with fasting levels less than or equal to 95 mg/dL were the best candidates for dietary therapy. They found that while women with fasting levels greater than 95 mg/dL improved in their control only up to 1 week, women with levels less than or equal to 95 mg/dL continued to show improvement up to 2 weeks. They recommended that women be treated with dietary therapy for at least 2 weeks before insulin is instituted. 

14. Lapolla A, Dalfra MG, Fedele D. Insulin therapy in pregnancy complicated by diabetes: are insulin analogs a new tool? Diabetes Metab Res Rev. 2005;21(3):241- 252 (Level III). 

15. Langer O, Conway DL, Berkus MD, Xenakis EM, Gonzalez O. A comparison of glyburide and insulin in women with gestational diabetes mellitus. N Engl J Med. 2000;343(16):1134-1138 (Level I). A randomized controlled trial of 404 women with GDM between 11 and 33 weeks’ gestation comparing glyburide and insulin therapies. Compared to 63% of women on insulin, 86% of women on glyburide reached targets. The rate of hypoglycemia was 2% for the women on glyburide compared to 20% for the women on insulin. There was a 4% failure rate for the women on glyburide. There was negligible placental transfer of glyburide. Neonatal outcomes were similar between the two groups. The investigators concluded that glyburide was comparable to insulin in the treatment of GDM. 

16. Nicholson W, Bolen S, Witkop CT, Neale D, Wilson L, Bass E. Benefits and risks of oral diabetes agents compared with insulin in women with gestational diabetes: a systematic review. Obstet Gynecol. 2009;113(1):193-205 (Level III). 

17. Coustan DR, Pharmacological management of gestational diabetes: an overview. Diabetes Care. 2007;30(Suppl 2): 206S-208S (Level III). 

18. Kjos SL, Schaefer-Graf U, Sardesi S. A randomized controlled trial using glycemic plus fetal ultrasound parameters versus glycemic parameters to determine insulin therapy in gestational diabetes with fasting hyperglycemia. Diabetes Care. 2001;24(11):1904-1910 (Level I). A randomized controlled trial to compare treatment of GDM based on maternal glucose versus relaxed glucose criteria and fetal abdomen circumference. The investigators found that using fetal parameters allowed 38% of women to avoid insulin therapy with no significant difference in neonatal outcome. 

19. Landon MB, Gabbe SG. Antepartum fetal surveillance in gestational diabetes mellitus. Diabetes. 1985;34(Suppl 2):50-54 (Level III). This study evaluated an antenatal surveillance protocol for women with GDM. A total of 97 women; 69 controlled with diet only and 28 treated with insulin. Hypertension was also seen in 21.6% of the women. Antenatal surveillance consisted of maternal activity assessment, clinical estimation of fetal weight, non-stress tests, and urinary estriol levels. Out of six women, four with hypertension required interventions. Sixteen infants, six of whom were identified in the antepartum period, were greater than 4000 g at delivery. No perinatal deaths occurred. The investigators concluded that outpatient management was effective in monitoring women with GDM. 

20. Kjos SL, Leung A, Henry OA, Victor MR, Paul RH, Medearis AL. Antepartum surveillance in diabetic pregnancies: predictors of fetal distress in labor. Am J Obstet Gynecol. 1995;173(5):1532-1539 (Level II-2). 

21. Metzger 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):251S-260S (Level III). 

22. Kjos SL, Peters RK, Xiang A, Schaefer U, Buchanan TA. Hormonal choices after gestational diabetes. Subsequent pregnancy, contraception, and hormone replacement. Diabetes Care. 1998;21(Suppl 2): 50B-57B (Level III). 

23. Kjos SL, Peters RK, Xiang A, Thomas D, Schaefer U, Buchanan TA. Contraception and the risk of type 2 diabetes mellitus in Latina women with prior gestational diabetes mellitus. JAMA. 1998;280(6):533-538 (Level II-2). 

24. Kim C. Managing women with gestational diabetes mellitus in the postnatal period. Diabetes Obes Metab. 2009 (Level II-2). 

25. Gunderson EP. Breast-feeding and diabetes: long-term impact on mothers and their infants. Curr Diab Rep. 2008;8(4):279-286 (Level III). 

26. Olson CM, Strauderman MS, Hinton PS, Pearson TA. Gestational weight gain and postpartum behaviors associated with weight change from early pregnancy to 1 year postpartum. Int J Obes Relat Metab Disord. 2003;27(1):117-127 (Level III). 

27. Mayer-Davis EJ, Dubelea D, Lamichhane AP, D’Agostino RB Jr, Liese AD, Thomas J. Breast-feeding and type 2 diabetes in the youth of three ethnic groups: the SEARCH for diabetes in youth case-control study. Diabetes Care. 2008;31(3):470-475 (Level II-2). This study evaluated offspring of women who participated in the Nurses’ Health Study II. They found that children aged 9 to 14 who were breast-fed exclusively were less likely to be overweight OR 0.66 (95% CI 0.53-0.82). These findings were independent of maternal BMI or diabetes status. 

28. Mayer-Davis EJ, Rifas-Shiman SL, Zhou L, Hu FB, Coliditz GA, William MW. Breast-feeding and risk for childhood obesity: does maternal diabetes or obesity status matter? Diabetes Care. 2006;29(10):2231-2237 (Level II-2).

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