# Clinical Cases: Gestational Diabetes

## Case 1: Newly Diagnosed Gestational Diabetes - Diet-Controlled

### Patient Demographics
- **Age:** 30 years
- **Sex:** Female
- **Occupation:** Administrative assistant

### Chief Complaint
"My doctor said my glucose test was abnormal."

### History of Present Illness
The patient is G2P1 at 26 weeks gestation. She underwent routine one-hour glucose challenge test (50 g) at 24 weeks, which returned at 156 mg/dL (threshold 140 mg/dL at her institution). She then completed a three-hour glucose tolerance test (100 g) with the following results:
- Fasting: 98 mg/dL (threshold 95)
- 1-hour: 195 mg/dL (threshold 180)
- 2-hour: 168 mg/dL (threshold 155)
- 3-hour: 130 mg/dL (threshold 140)

She has no symptoms of diabetes. Her first pregnancy was uncomplicated with a 3,400-gram infant delivered vaginally.

### Risk Factors for Gestational Diabetes
- BMI 32 kg/m2 (obesity)
- Family history of type 2 diabetes (mother)
- Hispanic ethnicity

### Physical Examination Findings
- **Vital Signs:** BP 118/74 mmHg, HR 76 bpm
- **BMI:** 32 kg/m2
- **General:** Well-appearing, overweight
- **Abdomen:** Gravid, fundal height 26 cm, appropriate for dates

### Diagnosis
**Gestational Diabetes Mellitus (A1GDM initially, pending diet trial)**
- Two abnormal values on 3-hour GTT (fasting and 1-hour)
- Meets Carpenter-Coustan criteria

### Initial Management

**Diabetes Education:**
- Referred to certified diabetes educator
- Glucose monitoring instruction
- Dietary counseling with registered dietitian

**Self-Monitoring of Blood Glucose (SMBG):**
- Fasting glucose every morning (goal <95 mg/dL)
- 1-hour or 2-hour postprandial after each meal
  - 1-hour goal: <140 mg/dL
  - 2-hour goal: <120 mg/dL

**Medical Nutrition Therapy:**
- 2,000-2,200 kcal/day (moderate restriction for BMI 32)
- Carbohydrate counting: 175-200 g/day
- Distribute carbohydrates: 3 meals + 2-3 snacks
- Complex carbohydrates, high fiber
- Evening snack to prevent overnight ketosis

**Physical Activity:**
- 30 minutes moderate walking after meals (improves postprandial glucose)

### Two-Week Follow-up

**Glucose Log Review:**
| Day | Fasting | Post-Breakfast | Post-Lunch | Post-Dinner |
|-----|---------|----------------|------------|-------------|
| 1   | 88      | 125            | 132        | 118         |
| 3   | 92      | 138            | 128        | 124         |
| 5   | 86      | 122            | 135        | 112         |
| 7   | 90      | 130            | 126        | 120         |

**Assessment:**
- All fasting values <95 mg/dL
- All postprandial values <140 mg/dL (1-hour)
- Excellent dietary compliance

**Diagnosis Refined:**
**Gestational Diabetes - Diet-Controlled (A1GDM)**

### Ongoing Management

**Continued Monitoring:**
- Weekly glucose logs reviewed
- Growth ultrasound at 32 weeks, then every 4 weeks

**Fetal Surveillance:**
- Diet-controlled GDM with good control: may not require antenatal testing
- Kick counts starting at 28 weeks
- NST at 40 weeks if not delivered

**Delivery Planning:**
- Diet-controlled GDM: can await spontaneous labor until 40+6 weeks
- No indication for cesarean based on GDM alone
- Induction at 41 weeks if not delivered

### Postpartum Management
- Discontinue glucose monitoring after delivery
- 75-g OGTT at 4-12 weeks postpartum to screen for persistent diabetes
- Counsel on 50% lifetime risk of developing type 2 diabetes
- Encourage weight loss, exercise, and breastfeeding (reduces diabetes risk)

### Clinical Image
![Glucose Monitoring](case_01_image.jpg)

**Image Description:** Self-monitoring blood glucose device with glucose log demonstrating the target values for fasting and postprandial glucose in gestational diabetes management.

**Attribution:** Educational illustration. Public domain.

---

## 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)
| Day | Fasting | Post-Breakfast | Post-Lunch | Post-Dinner |
|-----|---------|----------------|------------|-------------|
| 1   | 102     | 168            | 132        | 128         |
| 2   | 108     | 172            | 138        | 134         |
| 3   | 98      | 165            | 126        | 130         |
| 4   | 105     | 158            | 142        | 126         |
| 5   | 110     | 162            | 128        | 138         |

**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:**
| Day | Fasting | Post-Breakfast | Post-Lunch | Post-Dinner |
|-----|---------|----------------|------------|-------------|
| 1   | 88      | 132            | 126        | 122         |
| 3   | 92      | 128            | 134        | 118         |
| 5   | 86      | 124            | 128        | 126         |
| 7   | 90      | 136            | 122        | 120         |

**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
![Insulin for GDM](case_02_image.jpg)

**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.

---

## Case 3: Pregestational Type 1 Diabetes with Diabetic Ketoacidosis

### Patient Demographics
- **Age:** 26 years
- **Sex:** Female
- **Occupation:** Veterinary technician

### Chief Complaint
"I feel terrible. I've been vomiting all day and I can't think straight."

### History of Present Illness
The patient is G1P0 at 28 weeks gestation with type 1 diabetes since age 12. She has been using an insulin pump. She reports 24 hours of nausea, vomiting, and diarrhea that she attributed to a "stomach bug." She stopped eating and reduced her insulin doses because she wasn't keeping food down. She now feels weak, confused, and has rapid breathing.

### Past Medical History
- Type 1 diabetes x 14 years
- Diabetic retinopathy (mild, stable)
- Hypothyroidism on levothyroxine
- HbA1c at first prenatal visit: 7.2%
- Current insulin pump settings: basal 28 units/day, carbohydrate ratio 1:10

### Physical Examination Findings
- **Vital Signs:** BP 95/60 mmHg, HR 124 bpm, RR 28 (Kussmaul respirations), Temperature 99.1F
- **General:** Ill-appearing, confused, dry mucous membranes, fruity breath odor
- **Cardiovascular:** Tachycardic
- **Abdomen:** Gravid, diffuse tenderness, decreased bowel sounds
- **Neurologic:** Oriented to person only, lethargic

### Laboratory Findings
- **Blood Glucose:** 385 mg/dL (NOTE: can be lower in pregnancy DKA)
- **Arterial Blood Gas:** pH 7.18, pCO2 18, HCO3 8 (metabolic acidosis with respiratory compensation)
- **Anion Gap:** 26 (elevated, normal <12)
- **Serum Ketones:** Large positive
- **Beta-hydroxybutyrate:** 6.8 mmol/L (elevated)
- **Potassium:** 5.2 mEq/L (falsely elevated, will drop with treatment)
- **Sodium:** 128 mEq/L (corrected for glucose: 133)
- **BUN/Creatinine:** 28/1.4 (prerenal azotemia)
- **WBC:** 18,000 (stress response, but evaluate for infection)

### Fetal Assessment
- **Fetal Heart Rate:** Baseline 180 bpm, minimal variability, no accelerations
- Abnormal pattern attributed to maternal acidosis

### Diagnosis
**Diabetic Ketoacidosis in Pregnancy**
- Hyperglycemia (385 mg/dL)
- Metabolic acidosis (pH 7.18, HCO3 8)
- Elevated anion gap (26)
- Ketonemia

**Precipitating Factor:** Viral gastroenteritis with reduced insulin dosing

### Management (ICU Admission)

**1. Aggressive Fluid Resuscitation:**
- Normal saline 1 L bolus over first hour
- Then 500 mL/hour for next 4 hours
- Switch to 0.45% NS when glucose <250

**2. Insulin Therapy:**
- Discontinue insulin pump
- Regular insulin drip: 0.1 units/kg/hour (start at 7 units/hour)
- Goal: decrease glucose by 50-75 mg/dL per hour
- When glucose <250: add D5 to fluids and continue insulin to clear ketones

**3. Electrolyte Management:**
- Potassium: 5.2 initially, but will drop rapidly
- Add 40 mEq KCl/L to fluids when K <5.0
- Monitor K every 2 hours
- Hold potassium only if K >5.5

**4. Bicarbonate:**
- Not routinely given unless pH <6.9
- This patient: pH 7.18, so bicarbonate NOT given

**5. Identify and Treat Precipitating Cause:**
- Urine culture, blood cultures obtained
- Likely viral gastroenteritis

**6. Continuous Fetal Monitoring:**
- Abnormal FHR tracing expected to improve with maternal treatment
- Do NOT deliver for abnormal FHR during DKA
- Treat DKA first; most fetuses recover

### Clinical Course

**Hour 0-4:**
- Glucose: 385 → 280 mg/dL
- pH: 7.18 → 7.25
- K: 5.2 → 4.2 (potassium replacement started)

**Hour 4-8:**
- Glucose: 280 → 195 mg/dL
- D5 NS started, insulin continued
- pH: 7.25 → 7.32
- Anion gap closing

**Hour 8-12:**
- Glucose: 195 → 150 mg/dL
- pH: 7.32 → 7.38 (normalized)
- Anion gap: 12 (normalized)
- Beta-hydroxybutyrate: 0.8 mmol/L (normalizing)

**Fetal Heart Rate Improvement:**
- By hour 6: Baseline 160, moderate variability returning
- By hour 12: Reactive NST

**Transition to Subcutaneous Insulin:**
- When patient eating, pH >7.3, anion gap closed
- Overlapped SC insulin with drip for 2 hours
- Resumed insulin pump with adjusted settings

### Teaching Points

**DKA in Pregnancy:**
- Can occur at lower glucose levels ("euglycemic DKA")
- Develops faster due to accelerated starvation and respiratory alkalosis of pregnancy
- Fetal mortality historically high (up to 50%) but improved with modern management
- Abnormal FHR during DKA usually improves with maternal treatment

**Prevention:**
- Never stop insulin completely, even when not eating
- Sick day rules: check glucose and ketones every 4 hours
- Seek medical attention early for vomiting, illness
- Continue hydration

### Clinical Image
![DKA Pathophysiology](case_03_image.jpg)

**Image Description:** Diagram illustrating the pathophysiology of diabetic ketoacidosis, showing the cascade from insulin deficiency to hyperglycemia, lipolysis, ketogenesis, and metabolic acidosis.

**Attribution:** Educational illustration. Public domain.