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Difficulty: MediumEndocrinology and Metabolism

A 21-year-old man with a history of type 1 diabetes mellitus is brought to the emergency department due to altered mental status, nausea, and abdominal pain for the past 24 hours. He recently had a respiratory tract infection and missed several doses of insulin due to poor appetite. On physical examination, his temperature is 37.4°C (99.3°F), blood pressure is 90/60 mm Hg, pulse is 118/min, and respiratory rate is 28/min with deep, rapid breathing. His mucous membranes are extremely dry. Laboratory studies reveal:

Serum glucose: 580 mg/dL580\text{ mg/dL}
Serum sodium: 132 mEq/L132\text{ mEq/L}
Serum potassium: 4.9 mEq/L4.9\text{ mEq/L}
Serum bicarbonate: 11 mEq/L11\text{ mEq/L}
Arterial blood gas: pH 7.187.18
Serum ketones: Positive

Arrange the following management steps in the most appropriate chronological sequence for the acute and subacute treatment of this patient's condition.

  1. 1Administer a rapid intravenous bolus of 0.9% normal saline
  2. 2Initiate a continuous intravenous regular insulin infusion
  3. 3Add 5% dextrose to the maintenance intravenous fluids
  4. 4Administer a dose of subcutaneous long-acting basal insulin
  5. 5Discontinue the continuous intravenous regular insulin infusion

Answer

The correct sequence is: Administer a rapid intravenous bolus of 0.9% normal saline, followed by initiating a continuous intravenous regular insulin infusion, then adding 5% dextrose to the maintenance intravenous fluids, followed by administering a dose of subcutaneous long-acting basal insulin, and finally discontinuing the continuous intravenous regular insulin infusion.
The correct sequence strictly follows the established algorithm for treating diabetic ketoacidosis (DKA). Initial management focuses on aggressive fluid resuscitation with isotonic saline to stabilize hemodynamics and improve tissue perfusion. Once fluids are running and potassium is verified to be ≥3.3 mEq/L\ge 3.3\text{ mEq/L} (the patient's is 4.9 mEq/L4.9\text{ mEq/L}), an intravenous regular insulin infusion is started to suppress lipolysis and correct acidosis. As the insulin works, serum glucose falls faster than ketones clear. To prevent hypoglycemia while waiting for the anion gap to close, 5%5\% dextrose is added to the fluids when glucose reaches 200−250 mg/dL200-250\text{ mg/dL}. Finally, once the gap closes and the patient is stable to eat, a subcutaneous basal insulin dose is given. The intravenous insulin drip is discontinued 1-2 hours later to provide necessary overlap and prevent rebound DKA.

Step-by-Step Solution

1
Restore intravascular volume.
Administer 0.9% normal saline bolus.
The patient is hypotensive and severely dehydrated due to osmotic diuresis. Volume resuscitation is the absolute first step in management.
2
Correct hyperglycemia and ketonemia.
Initiate continuous intravenous regular insulin.
Insulin inhibits lipolysis and ketone production. It is safe to start immediately after fluids because the initial serum potassium is adequate (4.9 mEq/L).
3
Prevent hypoglycemia during treatment.
Add 5% dextrose to maintenance intravenous fluids.
Glucose levels typically normalize before ketoacidosis resolves. Dextrose is required to allow the continuation of the insulin infusion until the anion gap completely closes.
4
Transition to maintenance therapy.
Administer subcutaneous long-acting basal insulin.
Once the ketoacidosis resolves (anion gap closes, pH > 7.3) and the patient can eat, long-acting insulin must be administered before stopping the acute treatment.
5
Cease acute intravenous therapy.
Discontinue the continuous intravenous regular insulin infusion.
The intravenous insulin infusion should be discontinued 1 to 2 hours after the subcutaneous insulin is given. This overlap prevents an insulin-deficient window that could lead to rebound diabetic ketoacidosis.

Key Concept

Management Sequence of Diabetic Ketoacidosis (DKA)
Estimated Time:1m 30s
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Topics

Endocrinology and Metabolism

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