USMLE PRACTICE QUESTION OF THE WEEK

Question for February 13, 2026

A 58-year-old man with poorly controlled type 2 diabetes is brought to the hospital with confusion, polyuria, and abdominal pain. He has missed insulin doses for the past 3 days due to nausea. On exam, BP is 92/58 mmHg, pulse 122/min, respirations 30/min, and temperature 37.8°C (100.0°F). He appears dehydrated, with dry mucous membranes and poor skin turgor. His breath has a fruity odor.

Laboratory studies reveal:

Glucose: 540 mg/dL
Serum sodium: 132 mEq/L
Potassium: 4.8 mEq/L
Bicarbonate: 10 mEq/L
Arterial pH: 7.21
Anion gap: 28

Which of the following is the most appropriate next step in management?

A. IV bicarbonate infusion

B. Subcutaneous insulin and observation

C. IV potassium replacement before insulin

D. IV insulin and aggressive IV fluids

E. Oral hypoglycemic therapy

Get Detailed Explanation

Correct Answer:

D. IV insulin and aggressive IV fluids

Correct Answer Explanation:

This patient has diabetic ketoacidosis, with hyperglycemia, high anion gap metabolic acidosis, and dehydration. First-line management is aggressive isotonic IV fluids plus IV insulin. Potassium replacement is needed after insulin initiation if serum potassium falls, but with K⁺ near normal, insulin and fluids should begin immediately. IV bicarbonate is reserved for pH <6.9.

Further Insight:

Check potassium frequently, as insulin shifts K⁺ intracellularly.
Monitor for cerebral edema, especially in younger patients.