Hypoglycaemia associated with inadvertent insulin overdose

Inadvertent insulin overdose should be considered as a cause of severe hypoglycaemia in any patient with diabetes. Inadvertent insulin overdose can occur in patients in the community or in hospitalised patients. For management of inadvertent insulin-induced hypoglycaemia, see Severe hypoglycaemia in patients with diabetes or Nonsevere hypoglycaemia in patients with diabetes. Information on the type of insulin used and route of administration are vital to determine the method and duration of treatment, and the monitoring required.

Insulin overdoses often go unrecognised. An insulin overdose should be considered in patients who present with hypoglycaemia and require continuing intravenous glucose doses to maintain blood glucose concentrations more than 5 mmol/L.

To avoid inadvertent insulin overdose, when prescribing and giving insulin to a hospitalised patient, precautions must be taken; see Safety considerations for insulin use.

Inadvertent insulin overdose can occur in the community, for example in a patient who gives themselves a large dose of rapid-acting insulin instead of long-acting insulin. The patient can be managed in the community if they are able to keep eating regularly and checking their blood glucose concentration every 30 to 60 minutes, depending on the results. Blood glucose concentrations may take 4 to 8 hours to normalise. If the patient struggles to keep eating and/or checking blood glucose concentrations, they should be taken straight to hospital by ambulance, or by family or carers.

For patients who have taken a deliberate insulin overdose, arrange immediate transport to hospital by ambulance. Management can be complex and psychiatric assessment may be required. For further information, see Insulin poisoning.