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Hypoglycaemia
Hypoglycaemia is treated first — oral sugar if conscious, intravenous dextrose or glucagon if not — and investigated afterwards; in a patient without diabetes, blood is drawn during the episode for insulin, C-peptide and a sulfonylurea screen.
Why it matters in the exam
Most questions deal with a diabetic patient on insulin or a sulfonylurea with sweating, tremor, palpitations and confusion. The levels must be known (level 1: below 70 mg/dL; level 2: below 54 mg/dL; level 3: a severe event needing help) as well as the treatment: 15–20 g of oral glucose and a recheck after 15 minutes; if unconscious — intravenous dextrose (25 g) or glucagon. Hypoglycaemia from a sulfonylurea is prolonged and recurrent, so the patient is admitted and observed, sometimes with octreotide.
In a patient without diabetes the diagnosis needs Whipple's triad: symptoms, a low glucose (below 55 mg/dL) and relief with sugar. The work-up is done during an episode (or a 72-hour fast): high insulin and C-peptide — insulinoma or sulfonylurea use (hence a drug level is checked); high insulin with low C-peptide — injected insulin from outside. Other causes: alcohol, adrenal insufficiency, liver failure, sepsis, non-islet tumours and the state after bariatric surgery. In a patient with alcohol use disorder thiamine is given together with glucose.
Key points
- Level 1 below 70, level 2 below 54 mg/dL.
- Conscious: 15–20 g glucose and a recheck after 15 minutes.
- Unconscious: dextrose 25 g intravenously or glucagon.
- Sulfonylurea: admission and octreotide.
- No diabetes: Whipple, and during an episode insulin, C-peptide and a sulfonylurea screen.
Summary table
| Situation | Finding | Action | Exam note |
|---|---|---|---|
| Levels in diabetes | Level 1 below 70; level 2 below 54 mg/dL; level 3 severe | Treat and find the cause | Adjust the drug treatment |
| Conscious | Able to swallow | 15–20 g glucose, recheck after 15 minutes | Then a snack with complex carbohydrate |
| Unconscious | Unable to swallow | Dextrose 25 g intravenously or glucagon | Thiamine in alcohol use disorder |
| Sulfonylurea | Prolonged, recurrent hypoglycaemia | Admission, glucose infusion, octreotide | Especially glibenclamide in older people |
| No diabetes: high insulin and C-peptide | Insulinoma or sulfonylurea | Sulfonylurea level, pancreatic imaging | 72-hour fast for diagnosis |
| No diabetes: high insulin, low C-peptide | External insulin | Look for covert use | C-peptide separates them |
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Sources
- Endocrine Society Clinical Practice Guideline: Evaluation and Management of Adult Hypoglycemic Disorders, 2009 — Whipple's triad, evaluation of non-diabetic hypoglycaemia
- American Diabetes Association Standards of Care in Diabetes, 2025 — Hypoglycaemia classification and treatment
- Harrison's Principles of Internal Medicine, 21st edition (2022) — Hypoglycemia
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.