GESTATIONAL DIABETES MELLITUS (GDM)


Defined as glucose intolerance beginning or first recognized during pregnancy.

Risk Factors:
 -  Obesity
 -  Family history of GDM or type 2 diabetes
 -  Glycosuria at first prenatal visit.
 -  Polycystic ovarian syndrome
 -  Twin gestation
 -  Hypertension
 -  Chronic systemic steroid use.
 -  Maternal birth weight .9 lb or ,6 lb (prior macrosomic infants)
 -  Hispanics, Native Americans, and African-Americans are also at ↑ risk.

Universal preliminary screening:  

Cornerstones of GDM management
DIABETIC

D
iet
Information
Antenatal testing
Baby growth monitoring
Exercise
Test home blood glucose
Insulin/Metformin/glipizide
Check postpartum blood glucose

Symptoms/Exam

  • Often asymptomatic, or may present with polydipsia/polyuria or frequent infections, especially UTIs or yeast infections.
  • Obesity and acanthosis nigricans may also be seen

Diagnosis

Diagnostic criteria are as follows:

  • A1C > 6.5%
    or
  • Random blood glucose > 200 mg/dL on two separate occasions
    or
  • Fasting blood glucose > 126 mg/dL on two separate occasions
    or
  • 1-step method: 75-g, 2-hour OGTT (> 200 mg/dL)
  • 2-step method:
    • 50-g 1-h glucose challenge followed by fasting 100-g, 3-hour OGTT
      • If a 1 hr glucose challenge test is ↑ (> 140 after one hour), a 3 hr GTT should be performed within one week to confirm the diagnosis
      • A 3 hr OGTT, 100-g glucose challenge with two or more abnormal values:
        • > 95 fasting,
        • > 180 at one hour,
        • > 155 at two hours, or
        • > 140 at three hours.

Treatment

  • Offer nutritional counseling. Aim for 30 kcal/kg/day in women of normal weight, with carbohydrates making up no more than 40% of total caloric intake.
  • Encourage regular blood sugar monitoring and exercise regimens; offer diabetic education.

Non-pharmacologic Tx

-  Glucose monitoring:
    -Four times daily: Fasting and 2-hr postprandial
    - Goals: Fasting ,95 to 105 mg/dl; 2-hr postprandial ,110 to 120 mg/dl
    - Can also use 1-hr postprandial goal of ,130 to 140 mg/dl

 -  Dietary modifications aimed at glycemic control:
  - Follow a low-fat, high-fiber diet; avoid sugar and concentrated sweets; and eat small, frequent meals.
  - Nutrition counseling for diet that adequately meets the needs of pregnancy but restricts carbohydrates to 35% to 40% of daily calories.

For women with a body mass index > 30, restrict calories to 25 kcal/kg actual weight per day.
 -  Regular moderate exercise

Pharmacologic Rx

Begin if > 20% of glucose values are elevated after trial of diet control:

- Oral hypoglycemics:
 - Glyburide: begin at 2.5 mg qd and titrate up to a maximum of 20 mg qd (10 mg bid). Increase dose as needed by 2.5 to 5 mg/wk.
 - Metformin use in pregnancy remains controversial because it crosses the placenta.

- Insulin:
1. One commonly used regimen:
   - Insulin 0.7 U/kg/day SQ,
    - 2/3 of the total daily dose given in the morning and 1/3 of the total daily dose given in the evening.
    - 1/3 of each dose is given as short-acting insulin and the remaining 2/3 as NPH insulin.
- 1st trimester: 0.7 U/kg/day
- 2nd trimester: 0.8 U/kg/day
- 3rd trimester: 1.0 U/Kg/day
2/3 in AM 2/3 NPH
1/3 Regular Short-Acting
1/3 in PM 1/2 NPH
1/2 Regular Short-Acting

2. Another option:
   - If fasting values are elevated (> 95 or postprandial glucose is > 130 on > 2 occasions ),
                 - NPH at bedtime with initial dose of 0.2 U/kg.
   - If postprandial values are elevated,
                 - Rapid-acting insulin before meals with initial dose 1.5 U/10 g carbohydrate at breakfast and 1 U/10 g carbohydrate at lunch and dinner.
3. Long-acting insulin such as Lantus does not have sufficient data to determine whether it crosses the placenta; it may be continued in persons with preexisting diabetes who are well controlled but is not recommended in patients with newly diagnosed GDM
4. Glyburide and insulin have overall similar rates of clinical effectiveness and fetal safety.

Further Management

Intrapartum Management

- Goal is normoglycemia (80 to 110 mg/dl) using insulin and D5 lactated Ringer's IV fluid, NPO.
- Monitor glucose hourly
- Preparation for shoulder dystocia.
- If on Glyburide, discontinue in labor or 12 hr before a scheduled induction.
- Most laboring diabetic patients do not require insulin.

Antenatal Testing

Routine blood pressure and urine protein monitoring:
- Class A1: NST/AFI at 40 wk
- Class A2: weekly NST/AFI beginning at 32 wk or when insulin is started
- Poorly controlled diabetes, vascular complications, or hypertension:  Biweekly NST/AFI beginning at 28 wk and consider admission for initial glycemic control

Timing and Route of Delivery

 -  Class A1 (well controlled):  deliver by 41 wk
 -  Class A2:  deliver by 40 wk
 -  Offer elective cesarean section at 38 wk if estimated fetal weight > 4500 g
 -  Consider delivery by 37 wk if poor control or intrauterine growth retardation after confirmed fetal lung maturity by amniocentesis

Neonatal Management

 -  Check 30- and 60-min glucose
 -  Watch for signs of hypoglycemia, hypocalcemia, hyperbilirubinemia, and polycythemia

Postpartum Management

 -  Check fasting level before discharge; if abnormal, continue checking at home and early follow up with primary care physician to confirm diagnosis of DM
 -  6-wk postpartum visit: screen for diabetes with 2-hr 75g glucose tolerance test or two fasting values.
 -  If no evidence of DM, screen annually for DM and counsel on risk factor modification.

Referral

- Nutritionist
- High-risk obstetrician
- Maternal-fetal medicine
- Diabetes educator

Complications

Maternal Fetal Neonatal
Preeclampsia.
Future type 2 DM or GDM.
Operative delivery.
Polyhydramnios
Macrosomia.
Shoulder Dystocia.
↑ risk of Birth trauma.
Congenital malformations.
Hypoglycemia
Hypocalcemia
Hyperbilirubinemia
Polycythemia
Perinatal death
Future obesity and DM,
Impaired fine and gross motor functions; increased rates of inattention and hyperactivity
 

Pearls

  • Trials have shown that although treatment of mild gestational DM did not significantly reduce the frequency of a composite outcome that included stillbirth or perinatal death and several neonatal complications, it did reduce the risks of fetal overgrowth, shoulder dystocia, cesarean delivery, and hypertensive disorders.

Pevention

  • Regular exercise, maintenance of ideal body weight, and high-fiber low-glycemic diet

Pt & Family Educaiton

Gestational Diabetes Patient Information American Academy of Family Physicians
http://www.aafp.org/afp/20031101/1775ph.html

American Dietetic Association Consumer Nutrition Information and Referrals
http://www.eatright.org
Telephone: 800-366-1655

American Diabetes Association: Gestational Diabetes
http://www.diabetes.org|
800-DIABETES (800-342-2383)

NOAH: New York Online Access to Health
http://www.noah-health.org

National Institute of Child Health and Human Development Managing Gestational Diabetes: A Patient’s Guide to a Healthy Pregnancy
http://www.nichd.nih.gov/publications/pubs/gest_diabetes/
800-370-2943

Food and Nutrition Information Center Food Guide Pyramid
http://www.nal.usda.gov.