What is the treatment for a patient at 28 weeks gestation with an elevated 3-hour Glucose Tolerance Test (GTT)?

Treatment of Gestational Diabetes at 28 Weeks with Elevated 3-Hour GTT

Begin lifestyle intervention immediately as the essential first-line treatment, and add insulin therapy if glycemic targets are not achieved within 1-2 weeks of dietary modification and exercise. 1, 2

Initial Management: Lifestyle Intervention

Lifestyle modification is the cornerstone of GDM management and must be initiated immediately upon diagnosis. 1, 3

• Nutritional therapy: Implement calorie restriction with a low glycemic index diet to prevent postprandial hyperglycemia and reduce insulin resistance 3
• Exercise program: Add regular physical activity as part of the comprehensive lifestyle approach 3
• Self-monitoring: Initiate capillary blood glucose monitoring to assess glycemic control 4

Glycemic Targets to Achieve

Your patient must meet the following glucose targets to avoid pharmacologic therapy 2:

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

When to Escalate to Pharmacologic Therapy

Add insulin therapy if lifestyle modifications fail to achieve target glucose levels during follow-up visits. 1, 3

• Insulin is the preferred and recommended pharmacologic treatment for diabetes during pregnancy 1
• The guidelines explicitly advise against oral hypoglycemic agents during pregnancy due to lacking long-term safety data 1
• Metformin may be considered when insulin cannot be prescribed, though up to 46% of women on metformin may still require additional insulin to maintain target glucose levels 3

Monitoring Protocol

• Monitor blood glucose levels, HbA1c, and ketonuria to analyze the efficacy of conservative management 3
• Perform ultrasound surveillance to assess fetal abdominal circumference, as measurements exceeding the 75th percentile for gestational age may require more intensive glycemic control 2
• Note that 70-85% of women with GDM can achieve adequate control with lifestyle modification alone 2

Critical Clinical Considerations

The number of abnormal values on your patient's 3-hour GTT correlates with the severity of carbohydrate intolerance and risk of adverse outcomes. 5

• Patients with one or more abnormal GTT values have a 23-27% incidence of large-for-gestational-age (LGA) infants compared to 13% in those with normal GTT values 5
• Achievement of recommended glucose control decreases adverse outcomes to near-normal levels regardless of the number of abnormal GTT values 5
• Monitor for a rapid reduction in insulin requirements later in pregnancy, as this can indicate placental insufficiency requiring prompt evaluation 2

Delivery Planning

• Well-controlled GDM: Continue pregnancy to term with regular monitoring 2
• Suboptimal glycemic control despite maximal therapy: Consider earlier delivery, typically not before 37-38 weeks, with more intensive fetal surveillance 2
• Diet-controlled GDM: Can wait for spontaneous labor expectantly if no obstetric indications exist 3
• Insulin-requiring GDM: Elective induction at term is recommended 3

Postpartum Follow-up

• Screen for persistent diabetes at 4-12 weeks postpartum using a 75g OGTT 6
• Counsel about lifelong screening for diabetes or prediabetes at least every 3 years, as women with GDM have a 3.4-fold increased risk of developing type 2 diabetes 6