Sections View Full Chapter Figures Tables Videos Full Chapter Figures Tables Videos Supplementary Content + Print Section ++ For further information, see CMDT Part 19-20 Diabetes Mellitus in Pregnancy + Key Features Print Section ++ ++ Essentials of Diagnosis ++ Gestational diabetes Abnormal glucose tolerance in pregnancy Believed to be an exaggeration of the pregnancy-induced physiologic changes in carbohydrate metabolism Overt diabetes Diabetes mellitus that antedates the pregnancy Diagnosed in 50% of women with gestational diabetes at some point in their lifetime ++ General Considerations ++ Normal pregnancy can be characterized as a state of increased insulin resistance that helps ensure a steady stream of glucose delivery to the developing fetus Thus, both mild fasting hypoglycemia and postprandial hyperglycemia are physiologic These metabolic changes are believed to be hormonally mediated with likely contributions from human placental lactogen, estrogen, and progesterone Women with diabetes should undergo preconception counseling and evaluation to maximize pregnancy outcomes All pregnant women should undergo screening for gestational diabetes mellitus, either by history, clinical risk factors, or (most commonly) laboratory screening tests + Clinical Findings Print Section ++ ++ Symptoms and Signs ++ Excessive fetal growth Shoulder dystocia Preeclampsia Macrosomia Hypertension is common in overt diabetes Signs and symptoms of infections should be evaluated and promptly treated ++ Differential Diagnosis ++ Drugs: corticosteroids, thiazides, tacrolimus Diabetes insipidus Psychogenic polydipsia Nondiabetic glycosuria (benign) + Diagnosis Print Section ++ ++ Laboratory Tests ++ Euglycemia is considered to be 60–90 mg/dL (3.3–5.0 mmol/L) while fasting and < 120 mg/dL (< 6.7 mmol/L) 2 hours postprandially A screening 50-g glucose load is administered at 24-28 weeks gestation If this test is abnormal, the diagnostic test is a 100-g oral glucose tolerance test (Table 19–4) Initial tests include Complete chemistry panel HbA1c determination 24-hour urine collection for total protein and creatinine clearance Funduscopic examination ECG ++Table Graphic Jump LocationTable 19–4.Screening and diagnostic criteria for gestational diabetes mellitus.View Table|Favorite Table|Download (.pdf)Table 19–4. Screening and diagnostic criteria for gestational diabetes mellitus. Screening for gestational diabetes mellitus 50-g oral glucose load, administered between 24 and 28 weeks, without regard to time of day or time of last meal. Venous plasma glucose measured 1 hour later. Value of 140 mg/dL (7.8 mmol/L) or above in venous plasma indicates the need for a diagnostic glucose tolerance test. Diagnosis of gestational diabetes mellitus 100-g oral glucose load, administered in the morning after overnight fast lasting at least 8 hours but not more than 14 hours, and following at least 3 days of unrestricted diet (> 150 g carbohydrate) and physical activity. Venous plasma glucose is measured fasting and at 1, 2, and 3 hours. Subject should remain seated and should not smoke throughout the test. The diagnosis of gestational diabetes is made when two or more of the following venous plasma concentrations are met or exceeded: fasting, 95 mg/dL (5.3 mmol/L); 1 hour, 180 mg/dL (10 mmol/L); 2 hours, 155 mg/dL (8.6 mmol/L); 3 hours, 140 mg/dL (7.8 mmol/L). ++ Imaging ++ A specialized ultrasound is often performed around 20 weeks to screen for fetal malformations + Treatment Print Section ++ ++ Medications ++ Insulin should be given to women with persistent fasting hyperglycemia Insulin can be injected in a split dose mix of NPH and regular, administered twice daily Although insulin has long been regarded as standard care for women who require medical management, experience with the use of oral hypoglycemic agents, such as glyburide and metformin, is increasing Randomized controlled trials comparing insulin to oral therapy have identified generally similar maternal and neonatal outcomes However, long-term safety of oral agents has not been adequately studied Capillary blood glucose levels should be checked four times per day, once fasting and three times after meals The use of continuous insulin pump therapy may be helpful for some patients Adjustments in the insulin regimen may be necessary as the pregnancy progresses ++ Surgery ++ Cesarean sections are performed for obstetric indications ++ Therapeutic Procedures ++ Nutrition counseling Overt diabetes A well-planned dietary program is a key component, with an intake of 1800–2200 kcal/day divided into three meals and three snacks Fetal surveillance is indicated in third trimester Timing of delivery Dictated by the quality of diabetic control, the presence or absence of medical complications, and fetal status The goal is to reach 39 weeks (38 completed weeks) and then proceed with delivery Confirmation of lung maturity may be appropriate if preterm delivery is contemplated + Outcome Print Section ++ ++ Follow-Up ++ Patients should be evaluated 6–12 weeks postpartum with a fasting plasma glucose test or a 2-h oral glucose tolerance test (75 g glucose load) ++ Complications ++ Overt diabetes Fetal loss Spontaneous abortions Third trimester stillbirths Fetal malformations (eg, cardiac, skeletal, and neural tube defects) For the mother, the likelihood of infections and pregnancy-related hypertension are increased ++ Prevention ++ Prepregnancy HbA1c levels of 6% should be achieved to reduce the incidence of congenital anomalies ++ When to Refer ++ All women with diabetes should receive prepregnancy management by providers experienced in diabetic pregnancies ++ When to Admit ++ Failed intensive outpatient management of hypoglycemia or hyperglycemia Diagnosis of ketoacidosis Major complication of pregnancy + References Print Section ++ + +American College of Obstetricians and Gynecologists. Practice Bulletin No. 60. Pregestational diabetes mellitus. Obstet Gynecol. 2005 Mar;105(3):675–85. [Reaffirmed 2016] [PubMed: 15738045] + +American College of Obstetricians and Gynecologists. Practice Bulletin No. 180: Gestational diabetes mellitus. Obstet Gynecol. 2017 Jul;130(1):e17–37. [PubMed: 28644336] + +Bryant SN et al. Diabetic ketoacidosis complicating pregnancy. J Neonatal Perinatal Med. 2017;10(1):17–23. [PubMed: 28304323] + +Melamed N et al. Induction of labor before 40 weeks is associated with lower rate of cesarean delivery in women with gestational diabetes mellitus. Am J Obstet Gynecol. 2016 Mar;214(3):364.e1–8. [PubMed: 26928149] + +Moyer VA et al. Screening for gestational diabetes mellitus: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med. 2014 Mar 18;160(6):414–20. [PubMed: 24424622]