What are the management options for Gestational Diabetes Mellitus (GDM)?

Management of Gestational Diabetes Mellitus (GDM)

Lifestyle modification is the first-line treatment for GDM, with insulin as the preferred medication when pharmacological therapy is needed. 1

Diagnosis

GDM diagnosis is made using a 75g oral glucose tolerance test (OGTT), with one or more values meeting or exceeding:

• Fasting: ≥92 mg/dL
• 1-hour: ≥180 mg/dL
• 2-hour: ≥153 mg/dL 2

Treatment Algorithm

Step 1: Lifestyle Modifications

70-85% of women diagnosed with GDM can achieve glycemic control through lifestyle modifications alone 1:

Medical Nutrition Therapy (MNT)

• Individualized nutrition plan developed with a Registered Dietitian
• Dietary recommendations include:
  • Minimum 175g carbohydrates (35% of a 2,000-calorie diet)
  • Minimum 71g protein
  • 28g fiber daily 1
• Focus on quality carbohydrates to minimize postprandial glucose excursions
• Emphasize monounsaturated and polyunsaturated fats
• Limit saturated fats and avoid trans fats 1
• Weight gain according to 2009 National Academy of Medicine recommendations 1

Physical Activity

• Regular moderate-intensity exercise (20-50 min/day, 2-7 days/week) 1
• Both aerobic and resistance exercises have shown benefits in improving glucose outcomes and reducing insulin requirements 1

Step 2: Blood Glucose Monitoring

Target glucose levels:

• Fasting: <95 mg/dL
• 1-hour postprandial: <140 mg/dL
• 2-hour postprandial: <120 mg/dL 1

Step 3: Pharmacological Therapy

If glycemic targets are not achieved with lifestyle modifications:

Insulin Therapy (First-line)

• Insulin is the preferred medication for treating hyperglycemia in GDM as it does not cross the placenta to a measurable extent 1
• Dosing should be individualized based on blood glucose monitoring
• Insulin requirements typically level off toward the end of the third trimester 3
• A rapid reduction in insulin requirements may indicate placental insufficiency 1

Alternative Medications (Second-line)

• Metformin and glyburide should not be used as first-line agents as both cross the placenta 1

• Metformin concerns:

  • Crosses placenta readily, with cord blood levels equal to or higher than maternal levels 1
  • Follow-up studies show potential concerns for offspring, including higher BMI, increased waist-to-height ratio, and increased waist circumference in childhood 1, 2
  • 20-30% of women on metformin will ultimately require supplemental insulin 2

• Sulfonylureas concerns:

  • Cross placenta (glyburide concentrations in umbilical cord plasma are 50-70% of maternal levels) 1
  • Associated with higher rates of neonatal hypoglycemia and macrosomia than insulin 1

Telehealth Considerations

Telehealth visits for pregnant people with GDM have shown improved outcomes compared with standard in-person care, including:

• Reduced cesarean delivery rates
• Decreased neonatal hypoglycemia
• Lower rates of pregnancy-induced hypertension/preeclampsia
• Reduced preterm birth rates 1

Postpartum Follow-up

• Screen for persistent diabetes at 6-12 weeks postpartum 2
• Long-term follow-up every 1-3 years to screen for diabetes development 2
• Encourage breastfeeding to reduce obesity risk in offspring 2

Common Pitfalls and Caveats

1. Inadequate monitoring: Failure to monitor blood glucose regularly can lead to undetected hyperglycemia and poor outcomes.

2. Overreliance on oral agents: Despite convenience, metformin and glyburide should not replace insulin as first-line therapy due to placental transfer and potential long-term effects on offspring.

3. Excessive carbohydrate restriction: Severely restricting carbohydrates can lead to ketosis, which may be harmful to fetal development. Minimum 175g carbohydrates daily is recommended 1.

4. Ignoring postprandial glucose: Postprandial hyperglycemia is strongly associated with adverse outcomes. Both fasting and postprandial glucose levels must be targeted.

5. Delayed insulin initiation: When lifestyle modifications fail to achieve glycemic targets, prompt initiation of insulin therapy is essential to prevent adverse outcomes.

By following this evidence-based approach to GDM management, clinicians can effectively reduce maternal and fetal morbidity and mortality while improving long-term health outcomes for both mother and child.