Emergency Medicine Emergency Medicine · Endocrinology

Hypoglycaemia Causes

Hypoglycaemia (BG <3.5 mmol/L) is the most common endocrine emergency. In a comatose patient, it must always be excluded first — it is immediately reversible.

✦ The Mnemonic

"EXPLAIN Hypoglycaemia — Exogenous insulin and more"

Exogenous insulin/sulphonylureas · Physiological (fasting, exercise) · Liver failure · Adrenal insufficiency · Insulinoma · Malnutrition

E Exogenous insulin / Sulphonylureas Most common cause; excess insulin or insulin secretagogues; iatrogenic or deliberate

L Liver failure Glycogen storage depleted; impaired gluconeogenesis — alcohol, acute liver failure

A Addison's disease Cortisol deficiency → impaired gluconeogenesis + increased insulin sensitivity

I Insulinoma Rare; pancreatic beta cell tumour; Whipple's triad: symptoms + low glucose + relief with glucose

N Non-islet cell tumours IGF-2 secreting tumours — fibrosarcoma, hepatoma; hypoglycaemia in absence of diabetes

M Malnutrition + Neonatal Sepsis, prolonged fasting; neonatal hypoglycaemia — LGA infants of diabetic mothers

📚 Clinical Breakdown

Immediate treatment: conscious patient — 15–20 g fast-acting glucose (Lucozade, dextrose tablets, Hypostop gel). Unconscious/unable to swallow — IV dextrose 50 mL 10% (preferred over 50% — less vascular damage), or IM glucagon 1 mg. Recheck BG in 15 minutes.

Hypoglycaemia in non-diabetics (Whipple's triad): 1) symptoms of hypoglycaemia; 2) documented low blood glucose; 3) resolution of symptoms with glucose administration. All three criteria must be met. If Whipple's triad is positive — investigate for insulinoma (72-hour supervised fast + insulin:C-peptide ratio) or other causes.

Sulphonylurea-induced hypoglycaemia: prolonged action (glibenclamide can last 24–36 hours) — requires prolonged glucose infusion and monitoring, not just a single dextrose bolus. Admit for observation. Consider octreotide (somatostatin analogue — suppresses insulin secretion) for refractory sulphonylurea-induced hypoglycaemia.

First-line (unconscious) IV dextrose 10% 50 mL OR IM glucagon 1 mg

Whipple's triad Symptoms + low BG + relief with glucose

Sulphonylurea hypoglycaemia Prolonged — needs IV glucose infusion + monitoring

Always exclude in coma Immediate BM — hypoglycaemia is reversible

⭐ Clinical Pearl

Factitious hypoglycaemia: deliberate self-injection of insulin. Insulin levels are high, C-peptide levels are low (exogenous insulin suppresses endogenous production — no C-peptide). If both insulin and C-peptide are elevated — insulinoma or sulphonylurea overdose. The insulin:C-peptide ratio distinguishes the cause.

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