A 21-year-old male with Type 1 Diabetes presents with nausea, vomiting, abdominal pain, and Kussmaul respirations. Blood glucose is 420 mg/dL, arterial pH is 7.18, serum bicarbonate is 11 mEq/L, and serum potassium is 3.2 mEq/L. What is the critical first step before starting continuous intravenous insulin infusion?

Answer and explanation

Correct answer: A. Administer IV potassium chloride before starting insulin

  1. Step 1: In Diabetic Ketoacidosis (DKA), insulin drives potassium rapidly into cells.
  2. Step 2: If insulin is administered when serum potassium is < 3.5 mEq/L, severe, precipitous hypokalemia ensues, triggering fatal cardiac arrhythmias and respiratory muscle paralysis.
  3. Step 3: ADA guidelines mandate that insulin must be withheld and intravenous potassium replacement initiated (20-30 mEq/hr) until serum potassium reaches >= 3.5 mEq/L.
  4. Step 4: Simultaneously, isotonic fluid resuscitation (0.9% saline) is administered.
Answer
Administer IV potassium chloride before starting insulin.
Why not the others: 'Immediate IV regular insulin bolus' triggers fatal ventricular arrhythmias in hypokalemia; 'Rapid sodium bicarbonate bolus' causes paradoxical CNS acidosis and worsened hypokalemia; 'Withholding fluids' exacerbates hypovolemic shock and renal failure.

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