Obgyn · Year 3 · from Obgyn

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

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.

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