Toxicology: exogenous insulin administration: practice question

A Forensic 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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Forensic Medicine · Toxicology: exogenous insulin administration

Sample item

A non-diabetic patient is found unresponsive with a blood glucose of 25 mg/dL. Laboratory tests drawn at that time show a very high serum insulin and a suppressed C-peptide. A ward attendant had access to the drug store. What does this combination indicate?

ASulphonylurea ingestionBAn insulin-secreting tumourCAdministration of exogenous insulinDAdrenal insufficiency

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

The answer and the reasoning

C. Administration of exogenous insulin

Endogenous insulin is released together with C-peptide, so hypoglycaemia from an insulinoma or a sulphonylurea shows high insulin and high C-peptide. Injected insulin lowers glucose and suppresses the patient's own secretion, so insulin is high while C-peptide is low. This is the classic pattern in homicidal or factitious insulin use.

Option by option

A. Sulphonylurea ingestion
Sulphonylureas stimulate the pancreas, so C-peptide is also high.
B. An insulin-secreting tumour
An insulinoma raises both insulin and C-peptide.
C. Administration of exogenous insulin (correct)
Correct. High insulin with low C-peptide shows an external source.
D. Adrenal insufficiency
Adrenal insufficiency does not raise insulin levels.

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.

Questions about this Forensic Medicine question

What is the answer to this Forensic Medicine question?

The best answer is C, Administration of exogenous insulin. Endogenous insulin is released together with C-peptide, so hypoglycaemia from an insulinoma or a sulphonylurea shows high insulin and high C-peptide.

Why is "Sulphonylurea ingestion" not the answer?

Sulphonylureas stimulate the pancreas, so C-peptide is also high.

Why is "An insulin-secreting tumour" not the answer?

An insulinoma raises both insulin and C-peptide.

Why is "Adrenal insufficiency" not the answer?

Adrenal insufficiency does not raise insulin levels.

What concept does this question test?

It tests Toxicology: exogenous insulin administration in Forensic Medicine. Injected insulin lowers glucose and suppresses the patient's own secretion, so insulin is high while C-peptide is low. This is the classic pattern in homicidal or factitious insulin use.

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 Toxicology: exogenous insulin administration?

Learn postmortem changes with their timelines, and toxicology as poison, sign, test and antidote. Then use the flashcards and the other Forensic 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.