## Why Serum potassium ≥ 3.3 mEq/L is correct Regular insulin (marked **B**) is the ONLY insulin preparation that can be given intravenously and is the standard of care in DKA management. However, insulin drives potassium intracellularly, and initiating IV insulin in a hypokalemic patient (K+ < 3.3) can precipitate life-threatening hypokalemia and cardiac arrhythmias. Although total body potassium is always depleted in DKA (from osmotic diuresis), measured serum K+ must be ≥ 3.3 mEq/L BEFORE starting IV insulin infusion. Potassium replacement must be initiated simultaneously or beforehand. This is a critical safety checkpoint per ADA Standards of Care 2024 and KD Tripathi guidelines for DKA management. ## Why each distractor is wrong - **Serum bicarbonate < 15 mEq/L**: While bicarbonate is low in DKA, this is not a prerequisite for starting insulin. Insulin is started regardless of bicarbonate level; bicarbonate replacement is only considered if pH < 6.9. Bicarbonate level does not determine insulin initiation safety. - **Serum glucose > 300 mg/dL**: Insulin is started in DKA even at lower glucose levels (once K+ is adequate). The goal is to suppress ketogenesis by closing the anion gap, not merely to lower glucose. Glucose will be managed by switching IV fluids to dextrose-containing solutions once glucose drops to 200–250 mg/dL, while insulin continues. - **Serum creatinine < 1.2 mg/dL**: Renal function does not determine the safety of IV insulin initiation in acute DKA. Insulin works regardless of creatinine level. The critical electrolyte concern is potassium, not renal function at baseline. **High-Yield:** In DKA, ALWAYS check K+ ≥ 3.3 before IV regular insulin — insulin drives K+ intracellularly and can cause fatal hypokalemia if K+ is already low. [cite: KD Tripathi 9e Ch 19; ADA Standards of Care 2024]
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