Endocrine · Year 2 · from Endocrine

Case 1: New-Onset Type 1 Diabetes with Diabetic Ketoacidosis

Patient Demographics

  • Age: 16 years
  • Sex: Male
  • Occupation: High school student

Chief Complaint

"I've been drinking tons of water, going to the bathroom constantly, and I feel terrible."

History of Present Illness

A 16-year-old previously healthy male presents to the emergency department with 3 weeks of progressive polyuria, polydipsia, and unintentional weight loss of 15 pounds despite increased appetite. Over the past 2 days, he has developed nausea, vomiting, and diffuse abdominal pain. Today, his parents noticed he appeared confused and was breathing rapidly. He has no prior medical history and takes no medications. Family history is notable for maternal aunt with type 1 diabetes and grandmother with autoimmune thyroid disease.

Physical Examination

  • Vital Signs: BP 98/60 mmHg, HR 118 bpm, RR 28 (deep, labored - Kussmaul breathing), Temp 37.0°C
  • General: Thin, ill-appearing adolescent, lethargic but arousable
  • HEENT: Dry mucous membranes, fruity odor on breath (acetone)
  • Cardiovascular: Tachycardic, regular rhythm, weak pulses
  • Abdomen: Diffuse tenderness without guarding or rigidity (metabolic, not surgical)
  • Skin: Poor skin turgor, no acanthosis nigricans
  • Neurologic: Oriented to person only, slowed responses

Workup

  • Laboratory Studies:
  • Blood glucose: 485 mg/dL (markedly elevated)
  • Venous pH: 7.12 (acidosis)
  • Serum bicarbonate: 8 mEq/L (low)
  • Anion gap: 28 (elevated; Na 132 - Cl 96 - HCO3 8 = 28)
  • Serum ketones: Large positive (beta-hydroxybutyrate 8.2 mmol/L)
  • Potassium: 5.8 mEq/L (elevated - but total body K+ depleted)
  • Sodium: 132 mEq/L (falsely low due to hyperglycemia)
  • Corrected sodium: 137 mEq/L
  • BUN/Creatinine: 32/1.6 (prerenal azotemia from dehydration)
  • HbA1c: 12.4% (indicates chronic hyperglycemia)
  • Autoantibody Panel:
  • GAD65 antibodies: Positive
  • Islet cell antibodies (ICA): Positive
  • IA-2 antibodies: Positive
  • Insulin autoantibodies (IAA): Positive
  • C-peptide: 0.3 ng/mL (low, indicating minimal endogenous insulin production)
  • Urinalysis: Glucose 4+, ketones large

Diagnosis

Diabetic ketoacidosis (DKA) as presenting manifestation of Type 1 diabetes mellitus

Pathophysiology of DKA

  1. Absolute insulin deficiency (autoimmune beta cell destruction) plus counter-regulatory hormone excess (glucagon, cortisol, epinephrine, growth hormone)
  2. Hyperglycemia: Decreased glucose uptake + increased gluconeogenesis and glycogenolysis
  3. Osmotic diuresis: Glucosuria causes polyuria, leading to dehydration and electrolyte losses
  4. Ketogenesis: Insulin deficiency removes inhibition of lipolysis; free fatty acids flood liver and undergo beta-oxidation to ketone bodies (beta-hydroxybutyrate, acetoacetate, acetone)
  5. Metabolic acidosis: Ketone bodies are acids, leading to anion gap metabolic acidosis
  6. Potassium shifts: Acidosis and insulin deficiency cause K+ to shift extracellularly; serum K+ may be high despite total body depletion
  7. Abdominal pain: Common in DKA, can mimic surgical abdomen

Treatment

DKA MANAGEMENT PROTOCOL:

1. FLUID RESUSCITATION:

  • 0.9% NS 15-20 mL/kg (1-1.5 L) over first hour
  • Continue 0.9% NS at 250-500 mL/hr
  • Switch to 0.45% NS when corrected Na normal or high
  • Add D5 to fluids when glucose <200-250 mg/dL

2. INSULIN THERAPY:

  • Regular insulin IV bolus 0.1 units/kg (optional)
  • Regular insulin IV drip at 0.1 units/kg/hr
  • Target glucose reduction: 50-75 mg/dL/hr
  • Do NOT stop insulin until anion gap closes (even if glucose normalizes - add dextrose)

3. POTASSIUM REPLACEMENT:

  • If K+ <3.3: Hold insulin, give K+ 20-40 mEq/hr aggressively
  • If K+ 3.3-5.3: Add 20-30 mEq K+ to each liter of IV fluid
  • If K+ >5.3: Do not add K+; recheck in 2 hours
  • Monitor closely - K+ will drop rapidly with insulin therapy

4. BICARBONATE:

  • Only if pH <6.9 (controversial, rarely needed)
  • 100 mEq NaHCO3 in 400 mL water over 2 hours

5. MONITORING:

  • Glucose hourly
  • BMP every 2-4 hours
  • Anion gap calculation with each BMP

6. RESOLUTION CRITERIA:

  • Glucose <200-250 mg/dL
  • Anion gap <12
  • pH >7.3
  • Bicarbonate ≥18 mEq/L

7. TRANSITION TO SUBCUTANEOUS INSULIN:

  • Overlap IV and SQ insulin by 1-2 hours before stopping drip
  • Start basal-bolus regimen: 0.5-0.75 units/kg/day
  • Approximately 50% basal (glargine), 50% bolus (lispro with meals)

Long-term Type 1 Diabetes Management

  1. Lifelong insulin therapy (basal-bolus or insulin pump)
  2. Carbohydrate counting and insulin-to-carb ratios
  3. Self-monitoring of blood glucose or continuous glucose monitoring (CGM)
  4. Target HbA1c <7% (individualized)
  5. Diabetes education, nutrition counseling
  6. Screen for complications annually after 5 years
  7. Screen for associated autoimmune conditions (thyroid, celiac)

Clinical Pearl

Type 1 diabetes results from autoimmune destruction of pancreatic beta cells, leading to absolute insulin deficiency. Symptoms appear when ~90% of beta cells are destroyed, and patients often present with classic symptoms of polyuria, polydipsia, polyphagia, and weight loss. DKA occurs due to insulin deficiency combined with counter-regulatory hormone excess, resulting in uncontrolled lipolysis, ketogenesis, and metabolic acidosis. The presence of multiple autoantibodies (GAD65, IA-2, IAA, ZnT8) confirms the autoimmune etiology. In DKA management, the key principle is that insulin corrects the anion gap by stopping ketogenesis; therefore, insulin should continue until the gap closes, even if glucose normalizes (add dextrose to IV fluids). Potassium replacement is critical as total body potassium is depleted despite potentially normal or elevated serum levels, and K+ will drop rapidly with insulin therapy.

Clinical Image

Diagram illustrating the classic symptoms of diabetes mellitus including polyuria, polydipsia, polyphagia, and weight loss, along with the underlying metabolic derangements.

Image Source: Wikimedia Commons - "Main symptoms of diabetes" License: CC BY-SA 4.0 URL: https://commons.wikimedia.org/wiki/File:Main_symptoms_of_diabetes.svg

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