What is the recommended stepwise management of gestational diabetes mellitus (GDM) in pregnancy, including screening, dietary therapy, glucose monitoring, pharmacologic treatment, and postpartum follow‑up?

Management of Gestational Diabetes Mellitus in Pregnancy

Initial Management: Lifestyle Modifications First

All women diagnosed with GDM should begin treatment with medical nutrition therapy (MNT) and physical activity, as 70-85% can achieve glycemic control with lifestyle modifications alone. 1, 2

Medical Nutrition Therapy

• Refer immediately to a registered dietitian nutritionist experienced in GDM management to develop an individualized food plan. 1, 2

• Minimum daily nutritional requirements include 175g carbohydrates, 71g protein, and 28g fiber. 1, 2, 3

• Distribute carbohydrates across three small-to-moderate meals and 2-4 snacks throughout the day to limit postprandial glucose excursions. 2

• For overweight and obese women, modest energy and carbohydrate restriction is appropriate, but avoid starvation ketosis. 1

Physical Activity

• Prescribe at least 150 minutes of moderate-intensity aerobic activity per week, preferably spread throughout the week. 2, 3

Glucose Monitoring and Glycemic Targets

Self-monitor blood glucose in fasting and postprandial states to achieve the following targets recommended by the Fifth International Workshop-Conference on Gestational Diabetes Mellitus: 1, 2

• Fasting glucose <95 mg/dL (5.3 mmol/L)
• One-hour postprandial <140 mg/dL (7.8 mmol/L) OR
• Two-hour postprandial <120 mg/dL (6.7 mmol/L)

Postprandial monitoring is superior to preprandial monitoring as it is associated with better glycemic control and lower risk of preeclampsia. 3

Do not rely solely on A1C for monitoring in pregnancy, as it represents an average and may not capture physiologically relevant postprandial hyperglycemia that drives macrosomia. 1, 2

Pharmacologic Therapy: When and What to Use

Indications for Pharmacologic Treatment

Add pharmacologic therapy if glycemic targets are not achieved within 1-2 weeks of lifestyle modifications or if there are signs of excessive fetal growth. 1, 4

First-Line: Insulin

Insulin is the preferred and only recommended first-line pharmacologic agent because it does not cross the placenta to a measurable extent. 1, 2, 3, 4

Initial insulin dosing algorithm: 2

• Calculate total daily dose as 0.7-1.0 units/kg of current weight
• Distribute as 40% basal insulin and 60% prandial insulin
• Titrate frequently (weekly or biweekly in second trimester) as insulin resistance increases rapidly during pregnancy 1

Rapid-acting insulin analogs (aspart, lispro) are preferred over regular insulin for prandial coverage as they achieve postprandial targets with less hypoglycemia. 5

Long-acting insulin analogs (glargine, detemir) appear safe with similar maternal/fetal outcomes compared to NPH insulin. 5

Oral Agents: Not Recommended as First-Line

Metformin and glyburide are NOT recommended as first-line agents despite some efficacy data, because: 1, 3, 4

• Both cross the placenta to the fetus (metformin likely to a greater extent than glyburide) 1, 3
• Lack of long-term safety data for offspring is concerning 1
• High failure rates: glyburide fails in 23% and metformin fails in 25-28% of women 1
• Glyburide is associated with increased neonatal hypoglycemia and macrosomia compared to insulin 1

If oral agents are considered (when insulin cannot be prescribed), metformin has better safety profile than glyburide, but up to 46% may still require additional insulin. 6

Fetal and Maternal Surveillance

Monitor fetal growth with ultrasound to detect excessive fetal abdominal circumference, which may indicate need for treatment intensification even with seemingly good glycemic control. 1

Measure blood pressure and urinary protein at each prenatal visit as risk of hypertensive disorders is increased in women with GDM. 1

For women achieving glycemic targets with lifestyle modifications alone and appropriate fetal growth, surveillance beyond self-monitoring of fetal movements may not be necessary. 1

Delivery Timing

Women with diet-controlled GDM can await spontaneous labor in the absence of other obstetric indications. 6

Women requiring insulin therapy or with poor glycemic control should have elective induction at term recommended. 6

Postpartum Follow-Up: Critical and Often Forgotten

Screen for persistent diabetes or prediabetes at 4-12 weeks postpartum using a 75g oral glucose tolerance test with non-pregnancy criteria. 1, 3

Repeat screening every 1-3 years thereafter as women with GDM history have 50-70% risk of developing type 2 diabetes over 15-25 years. 1, 4

Both metformin and intensive lifestyle intervention prevent or delay progression to type 2 diabetes in women with a history of GDM. 3

Support breastfeeding as it provides immediate nutritional and immunological benefits for the baby and may offer longer-term metabolic benefits to both mother and offspring. 1

Review contraception options at regular intervals for all women of childbearing age, including those who are postpartum. 1

Team-Based Care and Telehealth

Refer to specialized centers or interprofessional team members when available, given the complexity of insulin management in pregnancy. 1, 2

Telehealth visits for GDM patients improve outcomes compared with standard in-person care, reducing cesarean delivery, neonatal hypoglycemia, and other complications. 2, 4

Common Pitfalls to Avoid

Do not prematurely escalate to medications before verifying adequate lifestyle modifications with dietitian consultation. 4

Do not delay insulin initiation in women with poor glycemic control on lifestyle modifications. 2

Do not use metformin for polycystic ovary syndrome beyond the first trimester. 2

Do not forget postpartum follow-up, as this is when long-term diabetes prevention strategies should be implemented. 4