Clinical presentation

Insulin poisoning causes hypoglycaemia and hypokalaemia (through intracellular shift of potassium).

Hypoglycaemia usually occurs within 1 to 2 hours after insulin injection, but may be delayed if a long-acting insulin preparation was administered. Large single injections can lead to delayed absorption due to a depot effect, prolonging toxicity.

Symptoms of hypoglycaemia may be blunted in patients with longstanding diabetes, but include:

• central nervous system (CNS) effects—dizziness, confusion, headache, drowsiness, seizures, coma
• autonomic effects—tremor, tachycardia, sweating, nausea.