What is the management plan for a patient with gestational diabetes mellitus (GDM)?

Management of Gestational Diabetes Mellitus

The management of gestational diabetes mellitus (GDM) should begin with lifestyle modifications, with insulin added only when glycemic targets cannot be achieved through diet and exercise alone. 1

Diagnostic Targets and Monitoring

• GDM is diagnosed when glucose values exceed established thresholds on oral glucose tolerance testing or when fasting glucose is ≥92 mg/dL 2
• Glycemic targets for GDM management are:
  • Fasting glucose <95 mg/dL (5.3 mmol/L) 1
  • One-hour postprandial glucose <140 mg/dL (7.8 mmol/L) 1
  • Two-hour postprandial glucose <120 mg/dL (6.7 mmol/L) 1
• Self-monitoring of blood glucose is essential to assess glycemic control and guide treatment decisions 3

First-Line Management: Lifestyle Modifications

Medical Nutrition Therapy

• An individualized nutrition plan should be developed with a registered dietitian familiar with GDM management 1, 3
• The diet should provide:
  • Minimum 175g of carbohydrate daily 1
  • Minimum 71g of protein daily 1
  • 28g of fiber daily 1
• Focus on distributing carbohydrates throughout the day to avoid postprandial glucose excursions 4
• Emphasize monounsaturated and polyunsaturated fats while limiting saturated fats and avoiding trans fats 1
• No specific caloric restriction is recommended unless clinically indicated; caloric needs are similar to those of pregnant women without GDM 1

Physical Activity

• Regular moderate-intensity exercise should be encouraged if not contraindicated 1, 5
• Exercise has been shown to improve glucose outcomes and reduce insulin requirements 1
• Effective exercise regimens include:
  • 20-50 minutes per day
  • 2-7 days per week
  • Moderate intensity aerobic, resistance, or combined exercise 1

Second-Line Management: Pharmacological Therapy

• Approximately 70-85% of women with GDM can achieve glycemic targets with lifestyle modifications alone 1, 3
• When lifestyle modifications fail to achieve target glucose levels, insulin should be initiated as the first-line pharmacological therapy 1
• Insulin is preferred because:
  • It does not cross the placenta to a measurable extent 1
  • It has proven efficacy in improving perinatal outcomes 1
  • It has the most extensive safety data in pregnancy 1

Oral Agents

• Metformin and glyburide should not be used as first-line agents because:
  • Both cross the placenta to the fetus 1
  • Long-term safety data for offspring are lacking 1
  • Failure rates requiring additional insulin are high (23-28%) 1
  • Glyburide has been associated with increased neonatal hypoglycemia and macrosomia compared to insulin 1, 3

Monitoring and Follow-up

• Blood glucose monitoring should be performed:
  • Fasting (morning)
  • 1 or 2 hours after meals 1
• For women requiring medication, fetal surveillance is recommended starting at 32 weeks gestation 6
• Telehealth interventions combined with in-person visits have shown improved outcomes compared to standard care alone 1
• Monitor for hypertensive disorders during pregnancy, as women with GDM have increased risk 3

Delivery Considerations

• For women controlling GDM with lifestyle modifications alone, delivery is recommended between 39/0 and 40/6 weeks 6
• For women requiring medication for glucose control, delivery between 39/0 and 39/6 weeks is recommended 6
• Consider earlier delivery if there are complications or poor glycemic control 6
• Assess for fetal macrosomia and discuss cesarean delivery if estimated fetal weight exceeds 4,500g 6

Postpartum Management

• All women with GDM should be screened for persistent diabetes 4-12 weeks postpartum using a 75g OGTT 2
• Women should be informed about their sevenfold increased risk of developing type 2 diabetes 2
• Preventive measures should be emphasized:
  • Weight management
  • Healthy diet
  • Regular physical activity
  • Breastfeeding 2, 6
• Follow-up screening for diabetes every 1-3 years is recommended 1

Common Pitfalls to Avoid

• Initiating pharmacological therapy before optimizing lifestyle interventions 1, 3
• Using oral agents as first-line therapy despite safety concerns and high failure rates 1
• Inadequate postpartum follow-up for diabetes screening 2
• Overlooking the importance of long-term follow-up for both mother and child 3, 2