Diabetes: hyperosmolar hyperglycaemic state: practice question

A General Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Medicine · Diabetes: hyperosmolar hyperglycaemic state

Sample item

A 68-year-old man with type 2 diabetes has had polyuria and increasing confusion for five days. Blood glucose is 900 mg/dL, serum sodium 150 mmol/L, pH 7.35, bicarbonate 22 mmol/L, and urine ketones are trace. What is the diagnosis with effective osmolality, and the first step in management?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Hyperosmolar hyperglycaemic state, effective osmolality about 350 mOsm/kg, with isotonic saline resuscitation first

Effective osmolality = 2 x sodium + glucose/18 = 300 + 900/18 = 300 + 50 = 350 mOsm/kg, above the 320 threshold. With near-normal pH and bicarbonate and minimal ketones this is HHS. Severe volume depletion is corrected first with isotonic saline, with insulin begun at a low rate once fluids are running and potassium is known, and osmolality is lowered gradually to avoid cerebral oedema.

Option by option

  • A. Hyperosmolar hyperglycaemic state, effective osmolality about 350 mOsm/kg, with rapid hypotonic fluid to normalise sodium in six hours

    Too rapid fall in sodium and osmolality risks cerebral oedema, so correction must be gradual.

  • B. Hyperosmolar hyperglycaemic state, effective osmolality about 350 mOsm/kg, with isotonic saline resuscitation first (correct)

    The calculation gives 350, and fluid resuscitation is the cornerstone of HHS management.

  • C. Hyperosmolar hyperglycaemic state, effective osmolality about 450 mOsm/kg, with intravenous sodium bicarbonate

    The arithmetic does not give 450, and bicarbonate is not indicated because there is no significant acidosis.

  • D. Diabetic ketoacidosis, effective osmolality about 300 mOsm/kg, with insulin infusion before any fluids

    The pH and bicarbonate are near normal with trace ketones, so this is not DKA, and insulin before fluids is wrong.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Hyperosmolar hyperglycaemic state, effective osmolality about 350 mOsm/kg, with isotonic saline resuscitation first. Effective osmolality = 2 x sodium + glucose/18 = 300 + 900/18 = 300 + 50 = 350 mOsm/kg, above the 320 threshold.

Why is "Hyperosmolar hyperglycaemic state, effective osmolality about 350 mOs…" not the answer?

Too rapid fall in sodium and osmolality risks cerebral oedema, so correction must be gradual.

Why is "Hyperosmolar hyperglycaemic state, effective osmolality about 450 mOs…" not the answer?

The arithmetic does not give 450, and bicarbonate is not indicated because there is no significant acidosis.

Why is "Diabetic ketoacidosis, effective osmolality about 300 mOsm/kg, with i…" not the answer?

The pH and bicarbonate are near normal with trace ketones, so this is not DKA, and insulin before fluids is wrong.

What concept does this question test?

It tests Diabetes: hyperosmolar hyperglycaemic state in General Medicine. With near-normal pH and bicarbonate and minimal ketones this is HHS. Severe volume depletion is corrected first with isotonic saline, with insulin begun at a low rate once fluids are running and potassium is known, and osmolality is lowered gradually to avoid cerebral oedema.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Diabetes: hyperosmolar hyperglycaemic state?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.