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Factitious disorder imposed on self — ABIM Board MCQ

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HardGeneral Internal MedicineFactitious disorder imposed on selfABIM Board

A 36-year-old nurse without diabetes mellitus has recurrent hospitalizations for confusion, diaphoresis, and documented hypoglycemia. During a supervised episode, her plasma glucose is 34 mg/dL, insulin is markedly elevated, C-peptide and proinsulin are suppressed, and beta-hydroxybutyrate is low. A serum sulfonylurea and meglitinide screen is negative. She denies using insulin despite having ready access to it at work. Review of her circumstances identifies no financial, occupational, legal, or drug-seeking incentive. Which of the following is the most likely diagnosis?

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Correct answer: A — Factitious disorder imposed on self

The correct answer is A, factitious disorder imposed on self. Markedly elevated insulin with suppressed C-peptide and proinsulin indicates exogenous insulin administration because pharmaceutical insulin does not contain C-peptide. The negative sulfonylurea/meglitinide screen excludes secretagogue ingestion. Her repeated presentation as ill, denial of insulin use, access to insulin, and absence of an external incentive support intentional illness induction for the patient role. Malingering also involves intentional deception but requires an identifiable external benefit, such as money, avoidance of work, or obtaining drugs. Somatic symptom disorder does not involve deliberate production of findings. Panic disorder cannot produce documented hyperinsulinemic hypoglycemia. An insulinoma secretes endogenous insulin and therefore generally causes elevated or inappropriately detectable C-peptide and proinsulin.

Reference: Awad DH, Gokarakonda SB, Ilahi M. Factitious Hypoglycemia. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; updated 2023 Sep 4. https://pubmed.ncbi.nlm.nih.gov/31194450/