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Difficulty: MediumMonitoring and Treatment Evaluation

A 2424-year-old man with a history of type 1 diabetes mellitus is brought to the emergency department with abdominal pain, nausea, and vomiting. Laboratory studies show a serum glucose of 580 mg/dL580 \text{ mg/dL}, bicarbonate of 12 mEq/L12 \text{ mEq/L}, and an anion gap of 2222. He is diagnosed with diabetic ketoacidosis. Assuming his initial serum potassium is 4.5 mEq/L4.5 \text{ mEq/L}, arrange the following management steps in the correct sequential order according to standard treatment protocols.

  1. 1Administer rapid intravenous volume expansion with isotonic saline.
  2. 2Initiate a continuous intravenous regular insulin infusion.
  3. 3Add 5%5\% dextrose to the intravenous fluid regimen.
  4. 4Administer the first dose of subcutaneous long-acting insulin.
  5. 5Discontinue the continuous intravenous regular insulin infusion.

Answer

The correct sequence for diabetic ketoacidosis management is: 1) Administer rapid IV volume expansion, 2) Initiate continuous IV regular insulin, 3) Add 5% dextrose when glucose falls below 250 mg/dL, 4) Administer subcutaneous basal insulin when the anion gap closes, and 5) Discontinue the IV insulin infusion 1 to 2 hours later.
The established protocol for DKA dictates a strict physiological sequence: circulatory collapse must be prevented first (IV fluids), followed by halting ketogenesis (IV insulin). Because insulin lowers glucose faster than it clears ketones, dextrose must be introduced mid-treatment to allow continued insulin administration without causing hypoglycemia. Finally, resolving the condition requires a transition to subcutaneous insulin, which must overlap with the IV infusion to ensure continuous coverage.

Step-by-Step Solution

1
Restore intravascular volume using isotonic crystalloid (0.9% normal saline).
Improves blood pressure, tissue perfusion, and facilitates renal clearance of glucose.
Severe dehydration is universally present in diabetic ketoacidosis (DKA). Fluid expansion must be the first step to prevent vascular collapse before insulin shifts fluid intracellularly.
2
Verify potassium is ≥3.3 mEq/L\geq 3.3 \text{ mEq/L} and start continuous IV regular insulin.
Stops ketone production and begins lowering serum glucose.
Insulin drives glucose and potassium into cells. Starting insulin without ensuring adequate potassium can cause life-threatening arrhythmias.
3
Monitor serial chemistries and add dextrose to IV fluids when glucose reaches 200-250 mg/dL200 \text{-} 250 \text{ mg/dL}.
Prevents iatrogenic hypoglycemia.
Glucose normalizes much faster than the ketoacidosis resolves. Insulin must be continued to clear ketones and close the anion gap, so exogenous dextrose is required.
4
Monitor the anion gap and administer subcutaneous insulin once the gap is ≤12\leq 12 and the patient can eat.
Prepares the patient for maintenance off the insulin infusion.
Once the underlying metabolic acidosis is corrected, the patient requires a transition to their long-term home subcutaneous regimen.
5
Wait 11 to 22 hours after the subcutaneous injection, then discontinue the IV insulin.
Completes the transition safely.
Subcutaneous insulin takes time to be absorbed and reach therapeutic blood levels. Stopping the drip simultaneously with the injection leaves a window with no insulin coverage, risking immediate rebound DKA.

Key Concept

The standard sequence of diabetic ketoacidosis (DKA) management involves initial fluid resuscitation, insulin therapy with careful potassium monitoring, addition of dextrose to prevent hypoglycemia while closing the anion gap, and a safe transition to subcutaneous insulin with appropriate overlap.
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Topics

Monitoring and Treatment Evaluation

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