Medication Error: A Tenfold Insulin Overdose

Immediate clinical actions, in priority order:

1. Assess and monitor the patient. Check capillary glucose now and repeat at least every 15–30 minutes initially. Rapid-acting insulin peaks within 1–3 hours, so the danger window is ahead, not behind. The patient being asymptomatic now is not reassuring.
2. Ensure IV access is patent and keep it available for glucose or glucagon administration.
3. Give fast-acting carbohydrate as a preventive measure and as per protocol, and ensure food is available. Because he has already received the insulin, early carbohydrate prevents a steep fall.
4. Escalate to the medical team and inform the nurse in charge, so a plan for monitoring and treatment is documented.
5. Prepare for hypoglycemia: have IV glucose (for example, 10% or 20% glucose) and glucagon available, and know the protocol for administering them.
6. Monitor for symptoms of hypoglycemia - sweating, tremor, confusion, palpitations, drowsiness - and for signs of neuroglycopenia.

Physiological reasoning: Ten times the prescribed dose of rapid-acting insulin will lower glucose substantially over the next few hours. The risk is greatest at the insulin's peak. Because the patient has type 2 diabetes and is eating, he may compensate to some degree, but the overdose is large enough that hypoglycemia is likely. Early carbohydrate and frequent monitoring are the interventions that prevent harm.

Managing the nurse:

• Separate the person from the error. The nurse is distressed; blaming her will not improve safety and may discourage future reporting. Speak to her privately, calmly, and without humiliation.
• Establish the facts: what was prescribed, what was read, what was given, and when. Ask her to show you the prescription and the medication chart.
• Support her and ensure she is not left alone with unsafe tasks while distressed; arrange for a senior colleague to supervise.
• Do not allow her to administer further insulin until the incident has been reviewed and she has been supported.

Documentation and reporting:

• Document the incident factually and contemporaneously in the patient's record: the drug, dose prescribed, dose given, time, route, the patient's condition, and the actions taken.
• Complete an incident report as per hospital policy. The incident report is for learning and risk management; it is not a substitute for the clinical record.
• Inform the medical team and the nurse in charge, and follow the hospital's medication error and duty-of-candour policy.
• Be honest with the patient as per the duty of candour: explain what happened, apologize, and explain what is being done.

Professional and ethical principles:

• Non-maleficence: the priority is to prevent harm to the patient.
• Beneficence and fidelity: act in the patient's interest and be truthful.
• Accountability: the error must be reported, not concealed.
• Just culture: the aim is to learn and improve systems (for example, double-checking high-alert medications and clearer decimal notation), not to punish the individual.

Contributing system factors:

• Look-alike decimal notation on the prescription ('1 unit' versus '10 units') - a classic high-alert medication hazard.
• High-alert medication without a second check. Insulin is a high-alert drug and should be independently double-checked by two nurses.
• Newly qualified nurse working a night shift on a short-staffed ward, which increases the risk of slips and misreading.
• Possible lack of a standard prescription format that writes units in words and avoids trailing zeros.

Preventive changes:

• Prescribing standards: write 'units' in full, never abbreviate, and avoid trailing zeros (write 1 unit, not 1.0).
• Independent double-check of all insulin doses by two registered nurses before administration, with both signing.
• Use of a standardized insulin chart with clear dose fields and a check box.
• Staffing and supervision: ensure adequate supervision for newly qualified staff on night shifts and avoid assigning high-alert medication tasks to an unsupported new nurse.
• Education and simulation on insulin safety and on reporting errors without blame.
• Audit and feedback: review medication incidents regularly and share learning across the ward.

Reasoning principle: Errors are usually the result of system weaknesses rather than a single careless person. The most effective prevention targets the system - prescribing, checking, and staffing - rather than simply telling staff to be more careful.