Obgyn · Year 3 · from Obgyn

Case 2: Gestational Diabetes Requiring Insulin

Patient Demographics

• Age: 35 years
• Sex: Female
• Occupation: Sales representative

Chief Complaint

"My blood sugars are still too high even though I'm following the diet."

History of Present Illness

The patient is G3P2 at 29 weeks gestation, diagnosed with GDM at 26 weeks. Despite strict adherence to medical nutrition therapy for 2 weeks, her glucose values remain elevated, particularly fasting and post-breakfast values. She checks her glucose 4 times daily and brings her log.

Past Medical History

• GDM in previous pregnancy (diet-controlled, delivered 4,100 g infant)
• PCOS diagnosed prior to pregnancy
• BMI 36 kg/m2

Glucose Log (Week 2 of Diet Therapy)

Assessment of Log:

• Fasting values: 4/5 days >95 mg/dL (consistently elevated)
• Post-breakfast values: 5/5 days >140 mg/dL (consistently elevated)
• Post-lunch and dinner: Most values at or near goal

Diagnosis

Gestational Diabetes Mellitus - Requiring Medication (A2GDM)

• Failed diet therapy trial (>20% values above target)
• Pattern: elevated fasting and post-breakfast

Management - Insulin Initiation

Fasting Hyperglycemia:

• Start NPH insulin at bedtime
• Initial dose: 0.2 units/kg = 0.2 x 95 kg = 19 units, round to 20 units
• NPH at 10 PM

Postprandial Hyperglycemia (Breakfast):

• Start rapid-acting insulin (lispro or aspart) before breakfast
• Initial dose: 4-6 units based on carbohydrate intake
• Titrate based on 1-hour post-breakfast values

Complete Regimen:

• NPH 20 units at bedtime (for fasting glucose)
• Lispro 6 units before breakfast (for post-breakfast glucose)
• Continue diet therapy for other meals

Insulin Adjustment Protocol:

• If fasting >95 for 2+ days: increase bedtime NPH by 2-4 units
• If post-meal >140 for 2+ days: increase pre-meal rapid insulin by 2 units
• Goal: >80% values at target

Two-Week Follow-up on Insulin

Glucose Log:

Current Insulin Doses (after titration):

• NPH 24 units at bedtime
• Lispro 8 units before breakfast

Assessment: Excellent control achieved

Fetal Surveillance (A2GDM)

Ultrasound Assessment:

• Growth ultrasound at 32 weeks: EFW 2,050 g (55th percentile)
• No evidence of macrosomia
• Polyhydramnios not present (AFI 15 cm)

Antenatal Testing:

• Weekly NST starting at 32 weeks
• BPP if NST non-reactive

Delivery Planning

Timing:

• Well-controlled A2GDM: delivery at 39+0 to 39+6 weeks
• If poorly controlled or complications: earlier delivery may be indicated

Mode of Delivery:

• EFW estimated at 38 weeks: 3,400 grams
• No indication for cesarean based on size
• Vaginal delivery anticipated with induction at 39 weeks

Intrapartum Glucose Management:

• Goal glucose during labor: 70-110 mg/dL
• Discontinue NPH on morning of delivery
• If glucose >110: start insulin drip
• If glucose <70: give D5 fluid

Delivery Outcome

• Induced at 39+2 weeks
• Vaginal delivery
• Male infant, 3,580 grams (68th percentile), Apgar 8/9
• Neonatal glucose at 1 hour: 52 mg/dL (normal, >40)
• No neonatal hypoglycemia

Postpartum

• Insulin discontinued immediately after delivery
• Glucose monitoring for 24-48 hours (all values normal)
• 75-g OGTT at 6 weeks postpartum: normal
• Counseled on diabetes prevention

Clinical Image

Image Description: Illustration showing insulin injection technique and sites appropriate for pregnancy, along with a sample insulin dosing regimen for gestational diabetes.

Attribution: Educational illustration. Public domain.

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